/ Dictionary / Index B basic plumage: Meaning and Definition of Find definitions for: ba'sic plum'age Pronunciation: [key] — Ornith. Ornith. the plumage assumed by an adult bird at its complete, usually annual, molt. (in birds having more than one plumage in their cycle of molts) the plumage of the first molt, usually the duller plumage. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. basic oxygen process basic process Related Content Daily Word Quiz: ounterfeit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language