(US, slang) San Quentin prison.

(slang, street name) The drug heroin.

(mathematical analysis) Upper bound function; see big O notation. / (slang, usually preceded by "the") Orgasm.

(baseball) A home run.

(military) A large artillery gun or one of the largest-caliber naval guns (as on a battleship).

(computing) Storing the most significant byte of a multibyte number at a lower address than the least significant byte; that is, "big end" first.

(idiomatic) The mouth of someone who talks too much, especially by making exaggerated claims or by inappropriately revealing information.

(informal) A large truck, an 18-wheeler.

(astronomy, especially US) A bright circumpolar asterism of the northern sky, said to resemble a ladle or cart. It is part of the constellation Ursa Major and includes the stars Mizar, Dubhe, and Alkaid. The other stars in it are Alioth, Megrez, Merak, and Phecda.

(idiomatic, informal, often sarcastic) Something very important or difficult; a matter of great concern; a considerable feat or achievement. / (idiomatic, informal) Someone very important; a VIP.