/ Dictionary / Index M methanal: Meaning and Definition of Find definitions for: meth•a•nal Pronunciation: (meth'u-nal"), [key] — n. Chem. formaldehyde. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: methanal (Thesaurus) methamphetamine methanation Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language