The Collaborative International Dictionary
Pin-hole pupil
Pupil \Pu"pil\, n. [F. pupille, n. fem., L. pupilla the pupil of the eye, originally dim. of pupa a girl. See Puppet, and cf. Pupil a scholar.] (Anat.) The aperture in the iris; the sight, apple, or black of the eye. See the Note under Eye, and Iris.
Pin-hole pupil (Med.), the pupil of the eye when so
contracted (as it sometimes is in typhus, or opium
poisoning) as to resemble a pin hole.
--Dunglison.