dis·tend / disˈtend/ • v. [tr.] cause (something) to swell by stretching it from inside: air is introduced into the stomach to distend it | [as adj.] (distended) a distended belly. ∎  [intr.] swell out because of pressure from inside: the abdomen distended rapidly.DERIVATIVES: dis·ten·si·bil·i·ty / -ˌtensəˈbilitē/ n.dis·ten·si·ble / -ˈtensəbəl/ adj.dis·ten·sion / -ˈtenshən/ n.

distend †stretch out or apart XIV; swell out from within XVII. — L. distendere; see DIS- 1, TEND 2.
So distension XV. — L.