cosset: [17] Cosset may originally have meant ‘someone who lives in a cottage’. Old English had a word cotsǣta ‘cottager’, which was formed from cot ‘cottage’ and *sǣt-, an element related to the verb sit. This disappeared from the language after the Old English period, but not before it was adopted into Anglo-Norman as cozet or coscet (forms which appear in Domesday Book).
It has been suggested that this is the same word as turns up in local dialects from the 16th century meaning ‘lamb reared by hand, pet lamb’ (that is, a lamb kept by a cottager rather than at liberty with the flock), and further that the notion of pampering a pet lamb gave rise to the verb cosset. [cosset etymology, cosset origin, 英语词源]