A-þrintan

According to the Old English Dictionary:

a-þrintan

p. -þrant, pl. -þrunton; pp. -þrunten [a out, þrintan to swell] To swell up; tumere :-- Ic ða wiht geseah, womb wæs aþrunten I saw the creature, its belly was swollen up, Exon. 109 b ; Th. 419, 7 ; Rä. 38, 2. a-þrintan