/ Dictionary / Index T trim rail: Meaning and Definition of Find definitions for: trim' rail" Pronunciation: [key] — Theat. Theat. the lower row of pins or cleats on a pin rail, used for tying off or fastening lines after lowering scenery into position. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. trimotor trim size Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language