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.
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.
Xylella fastidiosa is an aerobic, Gram-negative bacteria of the monophyletic genus Xylella. It is a plant pathogen, and is transmitted exclusively by xylem fluid feeding sap insects.
Xylocopa varipuncta, the valley carpenter bee, is one of three species of carpenter bee found from western New Mexico to northern California.