Same entry in Hesychius epsilon194 and other lexica. The headword -- masculine accusative singular or neuter nominative/accusative singular of the adjective e)gka/rsios (LSJ entry at web address 1) -- must be quoted from somewhere; perhaps Thucydides 6.99.3 and/or 7.4.1, the Athenian cross-wall, e)gka/rsion tei=xos, at the blockade of Syracuse; also 7.7.2 and cf. 2.76.6.
For other contexts see e.g. Aristotle, De mundo 393a28 (of the 'Sicilian' sea, from the perspective of a passage through the Mediterranean) and several times in Galen, of lateral cuts in dissection.
For the etymology cf. kappa 422. (An adjective ka/rsios is confined to lexicography, but note that Etymologicum Magnum 310.24-27 sees the root as kei/rw "I shear".)
For the synonym e)pika/rsios see LSJ s.v.