demarcation UK /ˌdɛm.ɑːˈkeɪ.ʃən/US /ˌdɛm.ɑɹˈkeɪ.ʃən/ noun3 •The act of marking off a boundary or setting a limit, notably by belligerents signing a treaty or ceasefire. •A limit thus fixed, in full demarcation line. •Any strictly defined separation.There is an alleged, in fact somewhat artificial demarcation in the type of work done by members of different trade unions. formsdemarcations