A particularly stealthy burglar, especially one who gains undetected entry through the use of agility.

(informal, endearing) A cat; a pussy. / (informal) A gentle or soft-hearted person. / The silky catkin of various willows. / (dated) A sexy woman.

A relationship in which two parties closely monitor and challenge one another in a suspicious or self-protective manner, often because each party is attempting to gain an advantage over the other.

A children's game in which one player (the "cat") attempts to break through a ring of players to catch another player (the "mouse") in the centre.

(slang, originally) A rich person who contributes to a political campaign. / (slang, derogatory) Any affluent person who is perceived to have profited from the labour of others.

(idiomatic) A highly sought-after and fancy example of something, usually referring to inanimate objects.

A hypothetical cat that is depicted as being surrounded by perfectly uncertain circumstances that make an external observer absolutely unable to deem the cat either alive or dead, especially if the possibilities of survival of the cat are expected to be analysed from the point of view of quantum mechanics. Typically, these circumstances involve the cat being inside a box while being the victim of a danger that may or may not kill it, such as radiation.

The thought experiment which was devised by Erwin Schrödinger, is usually considered a paradox, involves a Schrödinger's cat and is typically supposed to be analysed from the point of view of quantum mechanics.

(zoology) A domestic cat that has returned to or was born in a living situation without human care.

(uncountable) A children's game of forming string into various shapes around one's fingers. / (countable, idiomatic) Any complicated structure that appears to be without purpose.