An expert at something; a maverick, genius; a person owning a "first rank" talent.
A hole in one.
The ball marked with the number 1 in pool and related games.
A perfect score on a school exam.
A dollar bill.
A person who is asexual.
A military aircraft pilot who is credited with shooting down many enemy aircraft, typically five or more.
The best pitcher on the team.
Any of various hesperiid butterflies.
A card or die face so marked.
A single point or spot on a playing card or die normally indicating it as the prime, i.e. first and forefront. (in playing cards, of that series)
A point won by a single stroke, as in handball, rackets, etc.
A very small quantity or degree; a particle; an atom; a jot.
A serve won without the opponent hitting the ball.
Excellent.
Asexual, not experiencing sexual attraction.
To win a point by an ace.
To pass (a test, interviews etc.) perfectly.
To make an ace (hole in one).
Someone (especially one who is male) who is skilled in the work of fighting fire.
A safety inspector in coal mines.
An assistant on any locomotive, whether steam-powered or not.
A relief pitcher (reflecting the figurative analogy of rescuing the situation).
A person (originally a man) who keeps the fire going underneath a steam boiler (originally, shoveling coal by hand), particularly on a railroad locomotive or steamship.