from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An entity (usually a human) which provides presence information (who may be available and willing to communicate through communication services). For example, users of an instant messaging service (such as ICQ or MSN Messenger) are considered presentities. Presentities can have a status of being present, online, available, offline, or away.
- n. A group of humans, for example a collection of customer service agents in a call center that may be present. This presentity may be considered available if there is at least one agent ready to accept a call.
The word is a combination of words presence and entity and was first introduced in the Internet Engineering Task Force (IETC) RFC 2778. (Wiktionary)