/ Dictionary / Index S serotinal: Meaning and Definition of Find definitions for: se•rot•i•nal Pronunciation: (si-rot'n-l, ser"u-tīn'l), [key] — adj. pertaining to or occurring in late summer. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. serotherapy serotine Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language