(dated) An exclamation indicating that one is about to strike the person addressed, typically with a sword or other hand-held weapon.

(idiomatic) To enjoy oneself thoroughly; to have lots of fun or excitement.

(slang) To get angry; have a fit. / Used other than figuratively or idiomatically: see have, a, cow.

(informal) To become extremely upset. / (informal) To be in a state of frantic nervousness. / (literally) Usually of a female cat, to give birth to kittens.

(idiomatic, transitive, informal) To be attracted (sexually or romantically) to (someone); to fancy someone.

(idiomatic, informal) To be depressed; to have low morale; to feel sad.

An item that one must own, or a feature that is essential to a service, etc.

Essential to own.

(informal, usually with a negative) To know, understand or have a clue.

To engage in sex. / To engage in any sexual act.