1. The time between release of a message by the originator to receipt of the message by the addressee, as perceived by the end user. Synonym originator-to-recipient speed of service. 2. The time between entry of a message into a communications system and receipt of the message at the terminating communications facility, i.e., the communications facility serving the addressee, as measured by the system.
Source: from Federal Standard 1037C and from MIL-STD-188