one more time; once more; once again
one revolution; one rotation
first game; first round (e.g. of a tournament)
first time; first; initial
dose; installment; instalment
first-year (university) student; freshman; (one of the) first graduates of a new school
contest decided by a single round (bout); contest decided by a single roll of dice; one-shot game (contest); make-or-break game
first anniversary of a person's death; first death anniversary