50 synonyms for routine such as commonplace, customs, act, accustomed, and common. Routine is a noun, and its antonyms are spontaneity and chaos.
Customs, drill, formula, groove, habits, method, modus operandi, order, pattern, plan, practice, praxis, procedure, programme, regime, regimen, schedule, system, usages, ways, and wont.
Act, line, number, patter, performance, piece, shtick, spiel, and turn.
Accustomed, common, commonplace, conventional, customary, day-to-day, established, everyday, familiar, habitual, natural, normal, ordinary, regular, standard, typical, unexceptional, usual, and wonted.