Source : Webster's Revised Unabridged Dictionary (1913)

Callow \Cal"low\, a. [OE. calewe, calu, bald, AS. calu; akin to
   D. kaal, OHG. chalo, G. Kuhl; cf. L. calvus.]
   1. Destitute of feathers; naked; unfledged.

            An in the leafy summit, spied a nest, Which, o'er
            the callow young, a sparrow pressed.  --Dryden.

   2. Immature; boyish; ``green''; as, a callow youth.

            I perceive by this, thou art but a callow maid.
                                                  --Old Play
                                                  [1675].

Callow \Cal*low"\, n. (Zo["o]l.) [Named from its note.]
   A kind of duck. See {Old squaw}.

Source : WordNet®

callow
     adj : lacking experience of life; "a callow youth of seventeen"
           [syn: {inexperienced}, {naive}, {unsophisticated}]