define callow
callow. adj. 1. lacking experience of life; immature. 2. (Zoology) (of a young bird) unfledged and usually lacking feathers.allow. adjective inexperienced, juvenile, naive, immature, raw, untried, green, unsophisticated, puerile, guileless, jejune, unfledged Although he's 25, he still behaves like a callow youth in some ways.