(fandom slang) Initialism of Pokémon X and Y.

plural of XY problem

A communication problem where a person seeking help (for example, from a computing helpdesk) provides misleadingly incomplete information about the source of the problem and thus receives inaccurate or unhelpful suggestions about how to fix it.

(biology) The system that determines the sex of humans, most other mammals, some insects (Drosophila), and some plants (Ginkgo), in which females have two of the same kind of sex cell (XX) and males have two distinct sex cells (XY).

Alternative form of XY system

(biochemistry) Any of various enzymes that catalyze the hydrolysis of xylan

plural of xylan

(biochemistry) Describing any substance (such as a xylanase) that can break down a xylan.

(organic chemistry) An acid amide derivative of xylic acid, obtained as a white crystalline substance.

(archaic) Wood coal or charcoal, distinguished from mineral coal; lignite.