'nonupgradeable' originates from Modern English, formed by combining the prefix 'non-' (from Latin 'non' meaning 'not'), the verb/root 'upgrade' (from 'up' + 'grade', where 'grade' derives from Latin 'gradus' meaning 'step' or 'rank'), and the suffix '-able' (from Latin '-abilis' via Old French, meaning 'able to be').

'upgrade' developed in Modern English by combining 'up' (Old English 'up') and 'grade' (from Old French/Latin 'gradus'); the adjective 'upgradeable' was formed by adding the suffix '-able'; negation with the prefix 'non-' produced 'non-upgradeable', which is sometimes written without a hyphen as 'nonupgradeable'.

Initially the parts meant 'not' + 'able to be upgraded' in a literal compositional sense; over time the combined word has come to be used as a concise technical descriptor meaning 'incapable of being upgraded'.