The cardinal number immediately following forty and preceding forty-two.

(set theory) The second of the transfinite cardinal numbers; according to the continuum hypothesis, it corresponds to the number of real numbers.

(idiomatic) The place where one begins; a lack of progress.

Alternative form of one-upmanship

Occurring once, independent of any pattern; one-time. / Singular; unique; special; remarkable.

(idiomatic) Something that is done, created, etc. only once, and often quickly, simply, or improvisationally. / Something unique and remarkable.

(music) A style of drumming, prevalent in reggae and attributed to Winston Grennan, in which the snare and bass play on the same beat.

(golf) A hole that is completed by sinking the ball in a single shot or attempt, with one hit. / (by extension, idiomatic) Any rare, wonderful, or remarkable accomplishment.

(idiomatic) Alone; by oneself; without the companionship or assistance of others.

(cricket) The act of a batsman, running between the wickets, failing to ground himself or his bat behind the popping crease before turning for another run; the umpire's signal indicating this (the run does not count).