/ Dictionary / Index T thermoperiodicity: Meaning and Definition of Find definitions for: ther•mo•pe•ri•o•dic•i•ty Pronunciation: (thûr"mō-pēr"ē-u-dis'i-tē), [key] — n. Biol. the effect on an organism of rhythmic fluctuations in temperature. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. thermoperiodic thermophile Related Content Daily Word Quiz: wizened Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language