'consistently-employed' originates from English, specifically the words 'consistently' and 'employed', where 'consistently' ultimately derives from Latin 'consistere' (con- 'together' + sistere 'to stand') via Old French and Middle English, and 'employed' is the past participle of 'employ' (Old French 'employer', meaning 'to use').

'consistently' changed from Latin 'consistere' to Old French/Middle English forms as 'consistent' and then acquired the adverbial suffix '-ly' to become 'consistently'; 'employ' passed from Old French 'employer' into Middle English 'employ' and its past participle became 'employed'; in modern English the two were combined as the compound adjective 'consistently-employed'.

Initially, 'consistent' (from Latin) meant 'standing together' and 'employ' meant 'to use'; over time the combined phrase evolved into the modern usage meaning 'regularly or continuously employed'.