The headword is a single-word contraction of the prepositional phrase kata\ r(o/on. Orthography apart, the same gloss is found in Hesychius kappa889, and the Etymologicum Gudianum 300.36; cf. Apollonius' Homeric Lexicon 95.28. But only the Etymologicum Magnum 467.23 (s.v. i)e/nai) cites the one place the form ka\r r(o/on occurs: Homer, Iliad 12.33 (web address 1). The scholia to that passage, echoed by Hesychius, offer as a gloss the uncontracted phrase kata\ to\n r(o/on or kata\ to\n rou=n (showing Attic/Koine contraction of the vowels).