The Collaborative International Dictionary of English v.0.48:

Quinsy \Quin"sy\, n. [Contr. fr. squinancy, F. esquinancie, L.
   cynanche a sort of sore throat, Gr. ? sore throat, dog
   quinsy, fr. ? dog + ? to choke; cf. also L. synanche sore
   throat, Gr. ?. Cf. Hound, Anger, and Cynanche.] (Med.)
   An inflammation of the throat, or parts adjacent, especially
   of the fauces or tonsils, attended by considerable swelling,
   painful and impeded deglutition, and accompanied by
   inflammatory fever. It sometimes creates danger of
   suffocation; -- called also squinancy, and squinzey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

quinsy
    n 1: a painful pus filled inflammation of the tonsils and
         surrounding tissues; usually a complication of tonsillitis
         [syn: quinsy, peritonsillar abscess]