Pronunciation: (ôl"tur-nā'shun, al"-), [key]
1. the act or process of alternating or the state of being alternated.
2. alternate succession; repeated rotation: the alternation of the seasons.
3. Elect.a single fluctuation in the absolute value of an alternating current or voltage from zero to a maximum and back to zero, being equal to one half cycle.
4. Ling.variation in the form of a linguistic unit as it occurs in different environments or under different conditions, as between the -ed and -en forms of the past participle in danced and spoken or between the (t) and (d) pronunciations of the past tense suffix -ed in hopped and rubbed.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.