'Guitar' definitions:

Definition of 'guitar'

From: WordNet
noun
A stringed instrument usually having six strings; played by strumming or plucking

Definition of 'Guitar'

From: GCIDE
  • Guitar \Gui*tar"\, n. [F. guitare; cf. Pr., Sp., & Pg.guitarra, It. chitarra; all fr. Gr. ?; cf. L. cithara. Cf. Cittern, Gittern.] A stringed instrument of music resembling the lute or the violin, but larger, and having six strings, three of silk covered with silver wire, and three of catgut, -- played upon with the fingers. [1913 Webster]

Synonyms of 'guitar'

From: Moby Thesaurus