(fandom slang) A fan of the television series The X-Files.

(originally) A generation of people whose future is uncertain; a lost generation.

Alternative form of Xmas

A prize, usually a multi-million dollar monetary one, offered for a specific scientific or technological advance.

plural of x-axis

A folding chair with an X-shaped frame.

A simple stool having an X-shaped frame, often one that folds

A pair of flat or curved stretchers, on a chair etc., that often have a knob at the intersection

(genetics) Alternative spelling of X chromosome

(genetics) A mammalian sex chromosome. Cells of females have a pair of X chromosomes while cells of males have an X and a Y.