ve·sic·u·la·tion \ ̷ ̷ˌ ̷ ̷ ̷ ̷ˈlāshən\noun (-s) 1.: the condition of having or process of forming vesicles : the presence or formation of vesicles 2.: distribution or arrangement of vesicles < a variable vesiculation of the affected skin > < vesiculation of the two types of lava differs considerably — G.W.Tyrrell >