tour of duty(n = noun.time) duty tour, enlistment, hitch, term of enlistment, tour - a period of time spent in military service;
is a kind of period, period of time, time period

anti-dumping duty, breach of duty, civic duty, countervailing duty, customs duty, death duty, duty, duty assignment, duty period, duty tour, export duty, fatigue duty, fiduciary duty, filial duty, georges de la tour, grand tour, guard duty, import duty, jury duty, la tour, legal duty, line duty, line of duty, neglect of duty, off duty, on duty, on tour, package tour, point duty, sense of duty, sentry duty, shipboard duty, shore duty, stamp duty, tonnage duty, tour, tour de force, tour de france, tour guide, whistle-stop tour