. Substitute : fæsten-geweorc, es; n. Work at the repairing or construction of fortifications: one of the three obligations included in the trinoda necessitas. v. burh-bót, brycg-geweorc :-- Bútan fæstengewerce and fyrdsócne and brycggeweorce, C. D. ii. 111, 16. Fæstengeworce, 24. Freódóm from ǽghwelcum eorðlecum þeówdómæ bútan firdæ and fæstængewæorcæ and brycggewæorce excepto expeditione et arcis pontisque constructione, v. 218, 25. Fyrðe and brycge and festergeweorc héwe swá mon ofer eall folc dó, 151, 30.