Same entry in other lexica. As transmitted, the headword is the aorist indicative passive, third person singular, of kompa/zw; literally 'was made a boast of'. Its only extant occurrence outside lexicography is in Euripides, Heracles 64 (web address 1), but there it has none of the negative connotations of the lexicographers' glossing. The explanation of this mismatch lies in Hesychius epsilon1555, where e)kopi/sqh (sic) is glossed with h)path/qh ('was deceived') and ei)s o(/rkon dieyeu/sqh ('was tricked into an oath').
This verb, otherwise unattested, is kopi/zw (A) 'lie' in LSJ.