'chat' (modern English) ultimately comes from Middle English words such as 'chaten'/'chateren', probably imitative of rapid, light talk or sounds.

'chat' changed from Middle English 'chaten'/'chateren' (related to 'chatter') and developed into the modern English word 'chat'; the noun and verb senses were influenced by this same root and later extended to electronic/text-based 'chat'.

Initially it referred to 'chattering' or 'jabbering' (quick, trivial talk); over time it evolved into the broader modern sense of informal conversation, including online/text communication.