/ Dictionary / Index U underdrainage: Meaning and Definition of Find definitions for: un•der•drain•age Pronunciation: (un'dur-drā"nij), [key] — n. drainage of agricultural lands and removal of excess water and of alkali by drains buried beneath the surface. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. underdrain underdraw Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language