EtymologyMiddle English - saysen or seysen, meaning to seize. Old French - seisir or saisir which is from the low latin word sacire, generally referred to the same source as Goth satjan and Old English settan.
Seisin is the possession of such an estate in land as was anciently thought worthy to be held by a free man. (Williams, On Seisin, p. 2)
EtymologySeisin comes from Middle English saysen, seysen, in the legal sense of to put in possession of, or to take possession of, hence, to grasp, to seize. The Old French variations seisir, saisir, are from Low Latin sacire, generally referred to the same source as Gothic satjan, Old English settan, to put in place, set.
EnglandSeisin is of two kinds, in law and in deed. Seisin in law is where lands descend and the heir has not actually entered upon them; by entry he converts his seisin in law into seisin in deed. Seisin is now confined to possession of the freehold, though at one time it appears to have been used for simple possession without regard to the estate of the possessor. Its importance is considerably less than it was at one time, owing to the old form of conveyance by feoffment with livery of seisin having been superseded by a deed of grant, and the old rule of descent from the person last seised having been abolished in favor of descent from the purchaser.
At one time the right of the wife to dower and of the husband to an estate by curtesy depended upon the doctrine of seisin. The Dower Act (1833-1834), however, rendered the fact of the seisin of the husband of no importance, and the Married Women's Property Act 1882 practically abolished the old law of curtesy.
Primer seisin was a feudal burden at one time incident to the king's tenants in capite, whether by knight service or in socage. It was the right of the Crown to receive of the heir, after the death of a tenant in Capite, one year's profits of lands in possession and half a years profits of lands in reversion. The right was abandoned by the act abolishing feudal tenures (12 Car. II. c. 24, 1660).