What is "a blind boil"

Boil \Boil\, n. [Influenced by boil, v. See Beal, Bile.] A hard, painful, inflamed tumor, which, on suppuration, discharges pus, mixed with blood, and discloses a small fibrous mass of dead tissue, called the core.

A blind boil, one that suppurates imperfectly, or fails to come to a head.

Delhi boil (Med.), a peculiar affection of the skin, probably parasitic in origin, prevailing in India (as among the British troops) and especially at Delhi.