Often said to be from the root as in *kosnǫti and *kasati with an expressive infix *-x-, evolving semantically from “encountering” to “expressively paying honour” and hence “loving”, so Machek and repeated inter alios by Boryś, but, as Roman Jakobson remarks, it is in fact from the root for chicken: *kokošь(“hen”), Czechkokot(“cock”), Proto-Slavic*orzkošь(“voluptuousness, pleasure, orgasm”), Russianко́ко́(kókó, “egg”), Proto-Slavic*kočanъ meaning “head of cabbage”, “cob of corn”, “penis” across Slavic, the expression in Russianде́лать кому́-то ку́ры(délatʹ komú-to kúry) which is from Frenchfaire la cour but sounded as from кур(kur, “rooster”), etc. insinuate that *koxati is from an earlier *koksati evoking erotic rooster imagery. For this reason its early occurences in writing are rare, as it apparently was an unfine word.
