1. glove that encases the thumb separately and the other four fingers together;
The Collaborative International Dictionary of English v.0.48:
Mitten \Mit"ten\, n. [OE. mitaine, meteyn, F. mitaine, perh. of
Celtic origin; cf. Ir. miotog, Gael. miotag, Ir. & Gael.
mutan a muff, a thick glove. Cf. Mitt.]
1. A covering for the hand, worn to defend it from cold or
injury. It differs from a glove in not having a separate
sheath for each finger. --Chaucer.
2. A cover for the wrist and forearm.
To give the mitten to, to dismiss as a lover; to reject the
suit of. [Colloq.]
To handle without mittens, to treat roughly; to handle
without gloves. [Colloq.]
WordNet (r) 3.0 (2006):
n 1: glove that encases the thumb separately and the other four