(New American Roget's College Thesaurus)
1. regularity, periodicity; evenness, steadiness, constancy, consistency, invariability, punctuality; nonchaotic attractor; biorhythm; intermittence, alternation (see oscillation); beat, pulse, pulsation, cadence, swing, rhythm. See repetition.
2. (recurring cycle) round, bout, turn, period, circuit, cycle, routine; monthly bills, payments, etc.; period, menstruation, menses, catamenia, female disorder. Slang, floods, courses, little friend, monthlies, the curse, visitor, red mary.
a. anniversary, jubilee; diamond, golden, silver, wooden, paper, etc. anniversary; holiday; spring, winter, etc. break; centennial, biennial, etc.; feast, festival, celebration, fast day, birthday, saint's day, holy day.
b. Christmas, Easter, Thanksgiving, New Year's Day, Independence Day, Fourth of July, Memorial Day, Columbus Day, St. Patrick's Day, Labor Day, Groundhog Day, St. Valentine's Day, April Fool's Day, Halloween, All Hallows' or All Saints' Day, Dominion Day, Boxing Day; Washington's, Lincoln's, etc. Birthday, Martin Luther King Jr. Day, Veterans Day, Armistice Day, Presidents' Day; Admission Day, American Indian Day, Anzac Day, Arbor Day, Armed Forces Day, Armistice or Veterans Day, Pan American Day, Father's or Mother's Day, Human Rights Day, Robert E. Lee's Birthday, Sadie Hawkins Day, World Health Day, Jefferson Davis's Birthday.
c. Hanukkah, Passover, High Holy Day, Rosh Hashanah, Yom Kippur, Purim, Sukkoth.
d. Kwanza, junkanoo, Pinkster Day; Chinese New Year, Bairam, Bastille Day, Bon, Moharram, Peach Festival, Ramadan, Omisoka, Canada or Dominion Day, Simon Bolivar's Birthday, Spring Bank Holiday, Tet, Cinco de Mayo, Commonwealth Day, Diwali, Kenyatta Day, Flower Festival, Guy Fawkes Day.
Verbs — recur, return, reappear, come again, come [a]round, come in its turn, revolve, circle; beat, pulsate, throb, alternate, intermit, oscillate; come and go. Informal, roll around.
1. regular, steady, constant, uniform, even, symmetrical, consistent, punctual, systematic, methodical, orderly, unvarying, congruous; periodic[al], serial, recurrent, cyclical, seasonal, rhythmic[al], intermittent, remittent, alternate, every other; fixed, established, settled, continued, permanent; normal, natural, customary, habitual, usual, conventional, ordinary, typical, correct.
2. hourly, diurnal, daily, quotidian, tertian, weekly, biweekly, fortnightly, monthly, yearly; annual, biennial, triennial, centennial; secular, paschal, lenten; menstrual, catamenial.
Adverbs — regularly, normally, periodically, constantly, punctually; at regular intervals, like clockwork, at fixed periods, at stated times, from day to day, day by day; by turns, in turn, in rotation, alternately, every other day, off and on, round and round, year after year.
Antonyms, see irregularity.
(Roget's IV) n.
Syn. evenness, steadiness, uniformity, routine, constancy, consistency, invariability, predictability, rhythm, recurrence, system, congruity, homogeneity, punctuality, periodicity, swing, rotation, conformity, proportion, symmetry, balance, cadence, harmony, orderliness.
(Roget's Thesaurus II) noun The quality or condition of being usual: cus-tomariness, habitualness, normalcy, normality, ordinariness, prevalence, routineness, usualness. See USUAL.

English dictionary for students. 2013.