The element xenon was discovered in 1898 by British chemists Sir William Ramsay and Morris Travers. They named it from the Greek word 'xenos', meaning 'stranger' or 'foreign', because it was a new, rare, and unfamiliar gas found as a minor component in liquid air. This naming follows a tradition in chemistry where newly discovered noble gases were given names reflecting their elusive or peculiar nature. The literal meaning of 'stranger' thus evolved into the modern, specific scientific term for the chemical element with atomic number 54.

The entire word 'xenon' functions as a single, unsegmentable morpheme in English. It is a borrowing from the Greek adjective 'xenon', the neuter form of 'xenos' meaning 'strange, foreign, guest'.