<p><strong>Verb</strong></p><ul><li>(used without object) to utter a succession of small, tremulous sounds, as a bird.</li><li>to talk lightly and rapidly, especially of trivial matters; chatter.</li><li>to titter; giggle.</li><li>to tremble with excitement or the like; be in a flutter.</li></ul><p><strong>Noun</strong></p><ul><li>an act of twittering.</li><li>a twittering sound.</li><li>a state of tremulous excitement.</li></ul>