/ Dictionary / Index F formalin: Meaning and Definition of Find definitions for: for•ma•lin Pronunciation: (fôr'mu-lin), [key] — n. Chem. a clear, colorless, aqueous solution of 40 percent formaldehyde. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: formalin (Thesaurus) formaldehyde formalism Related Content Daily Word Quiz: winsome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language