'entrenchment' originates from French, specifically from the verb 'entrencher' (en- + 'trench'), where 'en-' meant 'in' and 'trench' (Old French 'trenche' / 'tranche') meant 'a cutting' or 'to cut'.

'entrenchment' changed via Middle English from verbs like 'entrenchen' (from Old French 'entrechier' / 'entrenchier') into modern English 'entrench' and then formed the noun 'entrenchment'.

Initially it meant 'to place in a trench or fortify' (literal military sense); over time it also acquired the figurative sense 'to establish firmly or make difficult to change'.