An unintended cavity filled with air in a casting product.
A top-facing opening to a cavity in the ground very near an ocean's shore, leading to a marine cave from which wave water or bursts of air are expelled.
The spiracle, on the top of the head, through which cetaceans breathe.
A vertical opening in the top of a computer case that lets hot air (primarily from the CPU heat sink) escape quickly.
A vent for the escape of steam or other gas.
To fill or be filled with air in an unintended cavity.
A piece made by splitting.
An opening, fissure, or V-shaped indentation made by or as if by splitting.
A disease of horses; a crack on the band of the pastern.
split, divided, or partially divided into two.
To syntactically separate a prominent constituent from the rest of the clause that concerns it, such as threat in "The threat which I saw but which he didn't see, was his downfall."