A round hole in an anvil designed to hold a pritchel or other round-shanked blacksmithing tool.

A square, tapered hole in an anvil used to hold certain blacksmithing tools

Conducted in secret; clandestine.

(US, idiomatic, informal) Synonym of ace up one's sleeve

A restaurant, shop or other establishment catering to customers that is particularly inconspicuous and easily overlooked. / (colloquial, chiefly Britain) An automated teller machine (ATM).

A hole in a vessel, such as a cask, that may be stopped with a bung. / (vulgar, slang) The anus.

(vulgar, slang) To have penetrative anal sex with.

The empty space in the center of a donut. / (US, Canada) A small ball-shaped pastry, made in the same manner as a donut, roughly the size of the hole in a donut.

(golf) A hole that is completed by sinking the ball in a single shot or attempt, with one hit. / (by extension, idiomatic) Any rare, wonderful, or remarkable accomplishment.

(mining) A hole in a mineshaft where an orebody is mined upwards until it breaks through the surface into the open air.