from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A Roman numeral representing forty (40).
- proper n. a fuck / damn.
- proper n. Tetrasomy X, a rare chromosomal disorder affecting females, caused by the presence of four X chromosomes instead of two present in the usual human karyotype.
- adj. X-rated, pornographic
From the (Australian) XXXX brand of lager, which was named after the practice of using X to indicate the strength of an alcoholic beverage, and which was advertised with the slogan "Australians couldn't give a XXXX for any other lager." (Wiktionary)
From X chromosome. (Wiktionary)
From X ("motion picture "adult" rating") (Wiktionary)