Also, a spectacular or dangerous act performed for entertainment value. Usually done by professional stuntmen, but sometimes by people who don't understand the phrase "do not try this at home" and find themselves in the hospital. Hmm, perhaps this does relate to the other definition...

Stunt (?), v. t. [imp. & p. p. Stunted (?); p. pr. & vb. n. Stunting.] [See Stint.]

To hinder from growing to the natural size; to prevent the growth of; to stint, to dwarf; as, to stunt a child; to stunt a plant.

When, by a cold penury, I blast the abilities of a nation, and stunt the growth of its active energies, the ill or may do is beyond all calculation.
Burke.

© Webster 1913

Stunt (?), n.

1.

A check in growth; also, that which has been checked in growth; a stunted animal or thing.

2.

Specifically: A whale two years old, which, having been weaned, is lean, and yields but little blubber.

© Webster 1913

Stunt (?), n. [Cf. Stint a task.]

A feat hard to perform; an act which is striking for the skill, strength, or the like, required to do it; a feat. [Colloq.]

An extraordinary man does three or four different "stunts" with remarkable dexterity.
The Bookman.

He does not try to do stunts; and, above all, he does not care to go in swimming.
L. Hutton.

© Webster 1913