To utter a succession of light chirping or tremulous sounds; chirrup. To speak rapidly and in a tremulous manner: twittering over office gossip. To giggle nervously; titter. To tremble with nervous agitation or excitement. To utter or say with a twitter: twittered a greeting. The light chirping sound made by certain birds. A similar sound, especially light, tremulous speech or laughter. Agitation or excitement; flutter.