Same entry in Photius and other lexica. The headword (which must be quoted from somewhere) is aorist optative passive, third person singular, of e)pitri/bw; cf. epsilon 2728, epsilon 2729, epsilon 2731. This verb can mean rubbing two objects one against the other, hence crushing and destroying or smoothing them by repetition, and a transferred sense from this is producing experience: see Chantraine s.v. tri/bw, and tau 953 on that verb.
[1] In Aristophanes, Thesmophoriazusae 557 (cf. Birds 1530), the second person singular e)pitribei/hs is used as an interjection with the meaning of wishing someone’s death. This, as Gaisford noted, may have been the reason for the addendum here.