@daniel
As #xmpp is the internet standard for chat, I'd go for chat address (or, in this case, chat ID) as we use #email address for email (not SMTP address, mutt address, k9 address and so on).

@martin @daniel since we're speaking of internet standards here, here are some quotes from https://www.rfc-editor.org/rfc/rfc6120#section-1.4
... The term "bare JID" refers to an XMPP address of the form <localpart@domainpart> (for an account at a server) or of the form
<domainpart> (for a server).

The term "full JID" refers to an XMPP address of the for
<localpart@domainpart/resourcepart> ...