Entry 2 senses · 2 variants Webster, 1913 Cosset /(k?s"s?t)/ · Cos·set · IPA /ˈkɒsɪt/ n. v. t. 01 n. A lamb reared without the aid of the dam. Hence: A pet, in general. 1. A lamb reared without the aid of the dam. Hence: A pet, in general. 02 v. t. To treat as a pet; to fondle. 1. To treat as a pet; to fondle. “She was cosseted and posseted and prayed over and made much of.” — O. W. Holmes.