chat¹ / chat/ • v. (chat·ted, chat·ting) [intr.] talk in a friendly and informal way: she chatted to her mother on the phone every day.• n. an informal conversation.PHRASAL VERBS: chat someone up inf. engage someone in flirtatious conversation. ∎  talk persuasively to someone, esp. with a motive.chat² • n. 1. [often in comb.] a small Old World songbird (Saxicola and other genera) of the thrush family, with a harsh call and typically with bold black, white, and buff or chestnut coloration. 2. any of a number of small songbirds with harsh calls, esp. a New World warbler, (genera Icteria and Granatellus), that typically has a yellow or pink breast.

chat 1 †chatter XIV–XV; converse easily and familiarly XVI. Shortening of CHATTER.
So chat sb. XVI. Hence chatty XVIII; see -Y 1.

chat 2 small bird. XVII. prob. imit.