term:

Seisin

seisin

or
sei·zin
[sēz-n]

n
[Anglo-French seisine, from Old French saisine act of taking possession, from saisir to seize, of Germanic origin]
1 : the possession of land or chattels: as
a : the possession of land arising from livery of seisin see also livery of seisin
b : the possession of a freehold estate in land by one having title thereto
2 : the right to immediate possession of an estate or to immediate succession [ of an heir upon death of the testator]