- Regularity of recurrence, punctuality.
- Irregularity of recurrence, uncertainty, etc.
(Adjectives). Infrequent, rare, unfrequent, uncommon.
(Adverbs). Seldom, rarely, scarcely, hardly, scarcely ever, ever, hardly ever, not often, unfrequently.
Once, once for all, once in a way, pro hac vice.
(Phrases). Once in a blue moon; angels' visits.
Periodicity (Substantives), intermittence, beat, pulse, pulsation, rhythm, alternation, pulsation, bout, round, revolution, rotation, turn.
Anniversary, centenary, bicentenary, tercentenary, etc.
Regularity of return, rota, cycle, period, stated time, routine.
(Phrase). The swing of the pendulum.
(Verbs). To recur in regular order or succession, to come round, return, revolve, alternate, come in its turn, beat, pulsate, intermit; to regularise.
(Adjectives). Periodic, periodical, recurrent, cyclical, revolving, intermittent, remittent, alternate, alternating, rhythmic, rhythmical, steady, punctual.
Diurnal, quotidian, annual, biennial, etc.
(Phrase). Regular as clockwork.
(Adverbs). Periodically, at regular intervals, at stated times, at fixed periods, punctually, de die in diem, from day to day.
By turns, in turn, in rotation, alternately, off and on, ride and tie.
In turns or shifts.
(Adjectives). Irregular, uncertain, unpunctual, capricious, desultory, unrhythmic, unrhythmical, fitful, flickering, casual.
(Adverbs). Irregularly, etc., by fits, by snatches, by starts, by catches, skippingly, by skips, now and then, occasionally, per saltum, à batons rompus.