/ Dictionary / Index T treenail: Meaning and Definition of Find definitions for: tree•nail Pronunciation: (trē'nāl", tren'l, trun'l), [key] — n. a wooden pin that swells when moist, used for fastening together timbers, as those of ships. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: treenail (Thesaurus) treen treenware Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language