English and French: nickname from Middle English, Old French co(u)sin, cusin (Latin consobrinus), which in the Middle Ages, as in Shakespearean English, had the general meaning ‘relative’, ‘kinsman’. The surname would thus have denoted a person related in some way to a prominent figure in the neighborhood. In some cases it may also have been a nickname for someone who used the term ‘cousin’ frequently as a familiar term of address. The old slang word cozen ‘cheat’, perhaps derives from the medieval confidence trickster’s use of the word cousin as a term of address to invoke a spurious familiarity. The patronymics constitute the most frequent forms of this name.