desertion (1) Desertion is where a husband or wife voluntarily and without reasonable cause leaves the other spouse against his or her will and with the intention of permanently ending the cohabitation. It is not essential that one or other party should actually depart from the matrimonial home if there is a complete abandonment of all matrimonial duties; desertion is not from a place but from a state of things. (2) To desert the armed forces is an offence under the Armed Forces Act.