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The majority of the definitions are courtesy of Scream And Fly.com.
I've left out a few that don't relate to bassboats and added a few definitions of my own.
Anti-Cavitation Plate: (Also referred to as Cavitation Plate).
The horizontal plate above the lower unit.  It is intended to prevent the prop from sucking surface air, ventilating into it and causing a cavitation-like effect. More useful on a deeply mounted outboard; on a high-performance or surfacing setups, it is of limited value due to it being out of the water while on plane.
Blowout:  This can occur when the ratio of air to water around the propeller gets so high that the prop is no longer grabbing water, but is trying to propel itself through air (or a relative vacuum).  This causes the prop to lose "bite" and then a chain of events occurs that can range from merely a "loose" steering feeling to a violent turn to the right (typically).  The speed at which this occurs varies with boat design and propeller design.
Blueprinting: (or blueprint) On an engine, it is bringing the specifications to a tighter tolerance range. On a hull, it is the process of making the bottom straight for the entire running surfaces and bringing any edges to a sharp edge, especially the hull/transom interface.  Check with the boat manufacturer before removing hooks and rockers that may have been designed into the hull for a purpose.
Cavitation:  The formation of "voids" or air inside the water stream, caused by low pressure near a surface.  Encountered when the water separates from the propeller.  Also called "ventilation", can cause propeller burn and can lead to "blowout".
Cavitation Burn:  Metal erosion on the propeller blades caused by air or gaseous bubbles on the positive side of the propeller blades.  Usually caused by excessive ventilation of the propeller.
Center Steer:  A hull setup that positions the steering helm (and driver) in the center of the boat, laterally.
Chine Walk: Severe side-to-side rolling of the boat.  It actually means to roll from chine to chine but it is also used for less severe rolling, although always severe enough to scare or cause a loss of control.  Essentially, this is a characteristic of high speed V-bottom boats, where the boat is balancing on the pad or very bottom, further aggravated by the drag of the lower unit.
Chinewalking must be compensated for by steering input from the driver.
Note: As a general rule, a properly setup bass boat will chinewalk less than one that has not been setup properly.
CLE: "Crescent Leading Edge" lower unit.  An older generation Mercury high performance lower unit with integral nosecone and low water pickups.  There were two designs of the CLE, both offering the same performance.  Designed for high speed surfacing applications, and originally equipped on 2.4 Bridgeport engines. No longer in production.
Cleaver Prop:  A stern lifting propeller design utilizing thin leading edges and square trailing edges, primarily for stern lift & tunnel boats.
Cone: (see Nosecone)
Crossflow:   A type of two-stroke technology.  The incoming fuel mixture is deflected by a dam on the piston and is forced up into the combustion chamber.
Cup:  Modified area of the trailing edge of the propeller that will and can affect holeshot and bow lift.
Dual Cable Steering:  Safety item.  Two steering cables that offer redundancy if one cable should fail.  They are also used to eliminate excess slack in the steering system, offering greater control.  The cables can attach to the engine from the same side or opposing sides.
Detonation:  Internal deterioration of aluminum components (usually the piston) resulting from lean mixtures, the collision of multiple flame fronts (excessive timing advance) and poor quality fuel.
ECU:  Electronic Control Unit - the "brains" of an electronic fuel injection system.  A computer that monitors engine systems and controls fuel delivery.
Gauge:  An instrument for monitoring information - speed, engine rpm, water pressure etc.
Galling:  Occurs when the threads of a bolt are damaged from lack of lubrication or excessive force of tightening.  This is not cross-threading.
Gelcoat:  The outer cosmetic layer of a fiberglass hull that provides a protective, high-luster finish.  Similar to paint, but epoxy-based and much thicker.
Holeshot:  How the boat performs from a dead stop to planing speed.  Generally,  a faster holeshot is more desirable.
Hook: (noun)  The shape of the hull where the bottom is concave; rather than at or near the transom. (A 'hook' at the very edge of the transom may be part of the hull design.) 
Opposite of a R.  A hook can be caused by insufficient support from the trailer, failure 
of the hull or actually designed into the hull by the manufacturer.
Hook:  (verb)  The tendency of some hulls to dart to the right or left due to drastic weight transfer to the bow, usually under extreme deceleration.  Also can be noticed in tight turns when one side of the hull wets out.
HP: (horsepower)  The power output of an engine or motor.  
Computed by using the following formula: Torque x RPM / 5252.
Hydrodynamics:  Pertains to the properties and forces of the flow of water over or around a surface.
Hydraulic Steering:  A steering system that utilizes fluid pressure to assist in steering action.
The system is comprised of a fluid pump, pressure lines and the steering cylinder.
Jackplate:  Also known as a transom jack or lift plate.  A mechanism that allows vertical adjustment of the outboard on the transom.  It also adds setback.  There are manual and hydraulic jackplates.
Kill Switch:  Emergency cut-off switch, usually actuated by a lanyard attached to the driver.
When pulled, the lanyard will actuate the switch, cutting the engine and fuel.
Kite: (verb)  The affect on a boat when too much air is packed under it at high speed; usually due to an inherent dynamic instability in high speed powerboats.  Caused by excessive trim, gusts of wind or launching off a wave.  Many times can cause a 'blowover'.
Layup:  Referring to the application layers, thickness and materials used in the construction of a fiberglass hull.
Lean (Lean Mixture):  A lower than normal fuel content in the engine's air-fuel mix.  Often results in higher operating temperatures, overheating, detonation, and increased power output.
Looper or Loop Charged:  Another type of two-stroke technology, different from the Crossflow.  The fuel mixture enters the cylinder on opposite sides and when it hits in the middle 
it is forced up into the combustion chamber.
Low Water Pickups:  Cooling water inlets on a lower unit.  These are on the nose, (or bullet) and are usually below the point.  Allows for high motor height and still deliver sufficient water for cooling.  The normal location of the water pickup for the water pump is on the sides of the lower unit above the gearcase.
Midsection:  The part of an outboard than connects the lower unit and the powerhead together.
Contains the steering mechanisms as well as the tilt/trim mechanisms.
Opposed Steering:  The steering cables attached to the outboard from the starboard and port sides.
Nose(or Cone)The foremost part of the gearcase on a lower unit.  It is also the aftermarket 'add-on' to create a longer aspect ratio of the gearcase.  It is the location for the 
low water pickups. As a general rule, an aftermarket nosecone is only beneficial to bass boats running 80+ mph. On slower boats, adding a nosecone could actually slow the boat down.
Pad:  The flat, center component of a V-bottom hull.  Pads offer V-bottom hulls greater lift compared to non-padded V-bottom designs.  (Also refers to the running surfaces of the outboard sponsons on a tunnel boat.)
Planing:  When the boat has achieved sufficient speed to ride onto its bow wave, a function of the hydrodynamic design of the hull.  Phase of operation that comes after "submerged" motion, has characteristics of significantly less drag.
Pitch: (Propeller)  The theoretical distance a propeller travels in one full rotation.
For example,  with a 25" pitch prop, the prop will "screw" through the water 25" in one full rotation. This is theoretical due to a certain amount of slippage being present.
Porpoising:  A constant rhythmic front to back pitching action of the boat, caused by a dynamic longitudinal instability.  Often results from improper dynamic balance of weight and aero/hydro-dynamic forces, and usually occurs at specific speed for a unique hull setup.
Over trimming the engine might cause this, whereby the bow is held up by prop thrust, but not enough to stabilize the condition.  (The boat will rise because of the prop thrust, the weight of the bow will drop it down, the prop will raise it again, etc.,etc.)  Trimming down (in) can eliminate it at low speeds.  The same action from the boat caused by not enough hull lift and subsequent falling of the bow back into the water.
Powerhead:  The actual engine itself.
Prop Shaft:  The output shaft of the lower unit where the propeller is mounted.
Prop Shaft Centerline:  Referenced to the boat bottom (pad) for prop height measurement.
Measured at zero trim with the cavitation plate parallel with the bottom of the boat.
Can be measured with a straight edge placed on the pad; the distance between the center of the prop shaft (point of the bullet of the gearcase), and the straight edge is then measured, and this is the distance that you are below (or above on certain high performance hulls), the pad.
Prop Walk:  A "paddle wheel" effect whereby the propeller will 'walk' across the water, sometimes caused by excessive engine height, not enough compensating angle in the torque tab and high-rake propellers.  Often occurs with 3 blade propellers less than with 4-5 blades.
Rake (propeller)The longitudinal angle of the propeller blades.  Usually, high rake props provide more bow lift and better holding power.  Rake and pitch are not always related.
Rich (Rich Mixture):  A higher than normal fuel content in the engine's air/fuel mix.
Often results in cooler operating temperatures, black exhaust deposits (carbon), plug fouling and decreased power output.
Rig: (noun)  The trailer and boat package as towed.  Also used to refer to the boat/engine combination.
Rig: (verb)  To install anything not part of the hull manufacture process.  Interior, gauges, wiring, engine, so on, to ready the boat for operation.
Rocker:  The shape of the hull where, rather than being flat it takes on a convex shape.
Opposite of Hook.  Can be caused by insufficient support from the trailer or failure of the hull.
Almost never an intentional design characteristic of the hull.
RPM:  "Revolutions Per Minute".  Almost always referring to engine crankshaft rotation speed.
Safety Switch: Safety Item.  See Kill Switch.
Setback:  The distance between the transom and the outboard.  Changes the center of gravity of the boat and allows the propeller to operate in less aerated water.
Setup:  Everything in the boat that contributes to the performance required.  A setup can be geared towards top speed, holeshot, midrange or a compromise of the three.
Usually referring to how a bassboat is setup, whether it has a jackplate, the engine height, prop being used, etc.
Skeg:  Lower rudder-like component of the gearcase. It is the lowest part of the motor.
Provides stability and tracking as well as counteracting steering torque when equipped with a Torque Tab. (Also provides some protection for the propeller.)
Splines:  Machined grooves on a driveshaft, propeller shaft or some other shaft that locks its mating counterpart in place, preventing rotation on the shaft.
Solid Engine Mounts:  Safety and performance item.  Solid aluminum or plastic composite, rather than rubber engine mounts.  Reduces slack in engine mount system, offering greater control and stability.  (For certain setups solid mounts can reduce chinewalk tendencies.)
Sportmaster:  Current generation Mercury high performance lower unit.  Includes a nosecone and low water pickups into the design, as well as stronger than stock internals.
Designed for high speed surfacing applications. Available for 2.0/2.4/2.5 and 3.0 liter applications.
Stator:  Wire winding assembly, usually located under the flywheel of an outboard engine.
Generates electricity for the ignition and charging system as the flywheel's magnets pass over the windings.
Stringers:  The "backbone" of a bassboat to provide it with its strength.  Many are wood stringers encapsulated in fiberglass, others are made of composite materials.  (Simply put, the
stringers are the "skeleton" of the structure and are between the floor and the hull.)
Stuffing:  The opposite of Kite.  A serious situation that occurs when the bow digs into a wave and the water pressure drives the bow down, in many cases causing severe damage and injury.
Tongue:  The part of the trailer that continues forward to connect to the hitch ball.
Weight of the trailer tongue should be approximately 10% of the entire rig weight as measured
at the hitch connection. (Too light a tongue weight will usually cause swaying of the trailer and generally poor towing characteristics.)
Torquemaster:  A heavy duty high performance Mercury lower unit that does not have a nosecone.  Designed for boats with heavier loads that require power trim for bow lift.
Current models include low water pickups, however earlier models did not.  Available for 2.5 and 3.0L applications.
Tilt:  The mechanism that lifts the outboard past the supports - out of the range of Trim.
May or may not be the same mechanism as trim.
Transom:  The back of the boat.  Usually concerning the attachment area for the outboard or the jackplate. 
Transom wedges:  Shims placed in between the outboard and the transom or jackplate that change the effective trim angles.
Trim:  The angle of thrust from the propeller.  The trim angle can be adjusted in (negative) or out (positive).  Zero trim is when the propshaft is parallel with the boat bottom.  Positive trim helps lift the bow, negative trim holds the bow down.
Trim Pump:  Electric pumping unit that pressurizes the engine hydraulic trim system.
Tuner:  The megaphone-shaped exhaust pipes inside the midsection.  Essentially, the tuner is the exhaust "header" of the outboard engine.
V-Bottom:  Hull design utilizing a centrally located, single running surface for lift.
These hull designs generally do not rely on air pressure for a significant portion of their lift.
Wheel Torque:  The tendency for the steering wheel to forcibly turn right.  Caused by the prop rotation and increases as the engine is jacked higher out of the water, becoming maximum when only one blade of the prop is entering the water. 
WOT:  Wide Open Throttle.