The Collaborative International Dictionary of English v.0.48:

bobbysoxer \bob"by*sox`er\ n.
   an adolescent girl wearing bobby socks (common in the 1940s);
   -- sometimes used for any adolescent girl, especially one
   following the latest youthful fashion .

   Syn: bobbysocker.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

bobbysoxer
    n 1: an adolescent girl wearing bobby socks (common in the
         1940s) [syn: bobbysoxer, bobby-socker]