chat V. to talk in a friendly informal way,esp. about things that are not important The two strangers chatted away like old friends. The old couple often chat while walking in their small garden after dinner. n. an informal friendly conversation They dropped in for a chat last night. The alumni often gather and have a chat about the old days.chat v. • to talk in a friendly informal way, esp. about things that are not important The two strangers chatted away like old friends. The old couple often chat while walking in their small garden after dinner. n. • an informal friendly conversation They dropped in for a chat last night. The alumni often gather and have a chat about the old days