The relationship between the amount of energy reaching an object (or a portion of it) and the amount leaving it. A good example of this is our Earth receiving energy from the sun, and giving off energy into the near future.

plural of ball hawk

A large, heavy sphere of leather or plastic filled with sand and used for athletic training or physical rehabilitation.

An electrical resistor whose resistance varies with the current passing through it, and thus tends to maintain a constant current

A headpiece worn usually by stage and film actors so as to appear bald on top without the necessity of shaving their scalps.

(uncountable) A pocket billiards (pool) game played with sixteen balls (a cue ball and fifteen object balls) on a pool table with six pockets.

(pool) To pot all one's colour balls and then the black ball (or eight-ball) without the opponent potting a single one.

(US) When landing on a US aircraft carrier: to sight the lights from the multi-colored optical landing system that shows a pilot to be on the correct approach path or how to correct the approach path.

(mathematics) A theorem stating that there is no nonvanishing continuous tangent vector field on the sphere; colloquially, that "you can't comb a hairy ball flat without creating a cowlick".

A player of a ball game; especially a basketball, baseball, or football player.