adjective
- not fledged; without sufficient feathers for flight, as a young bird.
- immature; callow.
adjective
- (of a young bird) not having developed adult feathers
- immature and undeveloped
adj.c.1600, of persons, “immature, not experienced,” from un- (1) “not” + past participle of fledge. Literal sense of “not yet covered in feathers” is recorded from 1610s.