The Collaborative International Dictionary of English v.0.48:
Girlish \Girl"ish\, a. Like, or characteristic of, a girl; of or pertaining to girlhood; innocent; artless; immature; weak; as, girlish ways; girlish grief. -- Girl"ish*ly, adv. -- Girl"ish*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
girlishly adv 1: like a girl; "she was girlishly shy"