In instant messaging (IM) terminology, a multiheaded client is a desktop or Web-based application that can be used to connect to multiple IM network accounts from a single user interface. Trillian, for example, is one of the most well-known multiheaded clients. This client lets users connect to their accounts on multiple public IM networks including ICQ, AOL Instant Messenger, MSN Messenger, Yahoo! Messenger and IRC.
May also be called multi-headed client.