'often-employed' originates from Modern English, a compound of 'often' (originally from Old English 'oft', meaning 'frequently') and 'employed' (from Old French 'employer').

'employ' changed from Old French 'employer' into Middle English as 'employen' and eventually became modern English 'employ'; 'often' developed from Old English 'oft' into the Modern English form 'often', and the compound 'often-employed' is a more recent Modern English formation.

Initially, the components meant 'frequently' ('often') and 'to use or engage' ('employ'); combined they have retained the straightforward sense of 'frequently used' in modern English.