Quinsy means: Quinsy is an old name for a peritonsillar infection. A peritonsillar infection is when there is pus or an abscess between the tonsils. It pushes the tonsil toward the uvula, the large soft tissue that hangs from the back side of your mouth. This condition is often associated with decreased mouth opening ability. The infection may spread to the neck, causing obstruction of the airway and potentially life-threatening complications.
(in Medical Dictionary)

What else does Quinsy mean?

An abscess is a condition that results in acute inflammation of the tonsils or surrounding tissues.
(in Merlin Dictionary)