/ Dictionary / Index D de plano: Meaning and Definition of Find definitions for: de pla•no Pronunciation: (di plā'nō, dē, dā), [key] — Chiefly Law. Chiefly Law. without argument. by manifest right; plainly. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. deplane deplete Related Content Daily Word Quiz: serendipity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language