Nos″tril (?), n. [OE. nosethril, nosethirl, AS. nosþyrl; nos for nosu nose + þyrel opening, hole, from þyrel pierced, for þyrhel, fr. purh through. √261. See Nose, and Through, and cf. Thrill.]
1. (Anat.) One of the external openings of the nose, which give passage to the air breathed and to secretions from the nose and eyes; one of the anterior nares.
☞ In sperm whales, porpoises, and allied animals, there is only one nostril, which is situated on the top of the head and called a spiracle.
2. Perception; insight; acuteness.
Methinks a man
Of your sagacity and clear nostril should
Have made another choice. B. Jonson.