'armrest' originates from English, formed as a compound of Old English 'earm' (meaning 'arm') and Old English 'ræst' (meaning 'rest').

'armrest' changed from the hyphenated or two-word forms 'arm-rest' / 'arm rest' in earlier usage and eventually became the modern single-word form 'armrest'.

Initially, it meant 'a rest for the arm' and over time has remained largely the same, though modern usage also covers built-in features (like storage or cup holders) incorporated into these supports.