The Collaborative International Dictionary of English v.0.48:

Routine \Rou*tine"\, n. [F., fr. route a path, way, road. See
   Route, Roterepetition.]
   1. A round of business, amusement, or pleasure, daily or
      frequently pursued; especially, a course of business or
      offical duties regularly or frequently returning.
      [1913 Webster]

   2. Any regular course of action or procedure rigidly adhered
      to by the mere force of habit.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

264 Moby Thesaurus words for "routine":
   Indian file, MO, accustomed, act, afterpiece, algorithm, approach,
   arranged, arrangement, array, articulation, assigned, attack,
   automatic, average, banal, bank, beat, beaten, beaten path,
   besetting, bit, boring, bureaucracy, bureaucratism, businesslike,
   buzz, catena, catenation, central, chain, chain reaction, chaining,
   chaser, chinoiserie, cliched, common, concatenation, concord,
   connection, consecution, constant, continuum, conventional, course,
   current, curtain, curtain call, curtain raiser, custom, customary,
   cycle, daily grind, deployment, descent, designated, disposal,
   disposition, divertimento, divertissement, dominant, drill, drone,
   endless belt, endless round, epidemic, epilogue, everyday, exode,
   exodus, expository scene, familiar, fashion, file, filiation,
   finale, form, formal, formation, formula, frequent, frequentative,
   gamut, gradation, grind, groove, guise, habit, habitual, hackneyed,
   harmonious, harmony, hoke act, hum, in hand, interlude,
   intermediary, intermediate, intermezzo, intermission, introduction,
   jog trot, layout, line, line of action, lineage, lines, lineup,
   manner, manner of working, many, many times, marshaling, mean,
   means, mechanical, medial, median, mediocre, medium, method,
   methodical, methodology, middle-of-the-road, middling, mode,
   mode of operation, mode of procedure, moderate, modus operandi,
   monotone, monotonous, nexus, normal, not rare, number,
   of common occurrence, oft-repeated, oftentime, order, ordered,
   orderly, ordinary, organization, pandemic, part, pattern, peace,
   pendulum, performance, perfunctory, periodicity, persistent, piece,
   plain, plan, plenum, popular, powder train, practice, predominant,
   predominating, prevailing, prevalent, procedure, proceeding,
   process, programmed, progression, prologue, proportion, queue,
   quiet, quietude, rampant, range, rank, recurrence, recurrent,
   recurring, red tape, red-tapeism, regnant, regular, regularity,
   reigning, repetitive, reticulation, rife, rotation, rote, round,
   row, ruling, run, run-of-the-mill, running, rut, scale, scene,
   schedule, scheduled, sequence, series, setup, shtick, single file,
   sketch, skit, song and dance, spectrum, squirrel cage,
   stand-up comedy act, standard, steady, stereotyped, string,
   striptease, structure, style, succession, swath, symmetrical,
   symmetry, system, systematic, tack, technique, tedious, the drill,
   the how, the way of, thick-coming, thing, thread, tier, tiresome,
   tone, track, train, tranquillity, treadmill, trite, turn,
   unchanging, uneventful, uniform, uniformity, unimaginative,
   uninteresting, unvaried, unvarying, usage, usual, way,
   well-ordered, well-regulated, well-trodden, well-worn,
   well-worn groove, windrow, wise, wont, wonted