Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
gussy, gussie (v.), gussied (adj.)
Gussy (sometimes spelled gussie) is a slang or Conversational verb meaning “to dress or decorate in a showy way”; it usually combines with up, as in They gussied up the apartment as best they could in preparation for her visit. The participial adjective is a frequent predicate adjective (again combining mostly with up), as in She was all gussied up for the dance.
