XY, xy, and variants may refer to:
XYY syndrome is a genetic condition in which a male has an extra Y chromosome. Symptoms are usually few.
Xylem is one of the two types of transport tissue in vascular plants, phloem being the other. The basic function of xylem is to transport water from roots to shoots and leaves, but it also transports nutrients.
The xylophone (from the Greek words ξύλον—xylon, "wood" + φωνή—phōnē, "sound, voice", meaning "wooden sound") is a musical instrument in the percussion family that consists of wooden bars struck by mallets.
Xylitol is a sugar alcohol used as a sweetener. The name derives from Ancient Greek: ξύλον, xyl[on], "wood" + suffix -itol, used to denote sugar alcohols.
Xylene (from Greek ξύλο, xylo, "wood"), xylol or dimethylbenzene is any one of three isomers of dimethylbenzene, or a combination thereof.
Xylocopa varipuncta, the valley carpenter bee, is one of three species of carpenter bee found from western New Mexico to northern California.
The XYZ Affair was a political and diplomatic episode in 1797 and 1798, early in the administration of John Adams, involving a confrontation between the United States and Republican France that led to an undeclared war called the Quasi-War.
Xylem Inc. is a large American water technology provider, enabling customers worldwide to transport, treat, test and efficiently use water in public utility, residential, commercial, agricultural and industrial settings.