Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., of uncertain origin, perhaps from a source related to Low German sippen "to sip," or from Old English sypian "absorb, drink in," related to supan "to take into the mouth a little at a time" (see sup (v.2)). Related: Sipped; sipping.
c.1500, from sip (v.).
1. Session Initiation Protocol. 2. Supplementary Ideographic Plane. (2003-12-26)