Person or entity whose name one does not want to mention but which is known to the person to whom one is speaking.

(mathematics) A branch of topology dealing with knots.

One of a class of childish jokes told as a dialog, and usually including a pun, in the following form:

(baseball) To cause a pitcher to be replaced by heavy hitting. / (idiomatic) To cause something to be replaced by something else.

A small knob.

(transitive) To give a knobbly surface to. / (transitive, metallurgy) To produce wrought iron by treating (semirefined puddled iron) on a hearth before shingling.

A course of study which must be completed by prospective London taxi drivers; consists of 320 routes through central London and many significant places.

The knowledge and skill to be able to (do something correctly).

(archaic, chiefly law) Sexual intercourse.

A rounded protuberance, especially one arising from a flat surface; a fleshy lump or caruncle. / A rounded control switch that can be turned on its axis, designed to be operated by the fingers.