"The N.E.D. recognizes eight nouns cob, with numerous sub-groups. Like other monosyllables common in the dial. its hist. is inextricable" [Weekley]. In the latest edition, the number stands at 11. Some senses are probably from O.E. copp "top, head," others probably from O.N. kubbi or Low Ger., all perhaps from a P.Gmc. base *kubb- "something rounded."