cream, Middle Irish ceó, milk; cf. Breton koavenn, which suggests a form keivo- (cf. glé from gleivo-), root kei, skei, shade, cover, as in Greek $$Gskiá, shadow, German schemen (do.)? The Breton koavenn has been refered to *co+hufen, Welsh hufen, cream. Cf. ceò, mist, "covering".
Etymological dictionary of the Gaelic language.
Alexander Gairm Publications.
1982.