Primer Seisin Law and Legal Definition

Primer seisin refers to a right which the king had, when any of his tenants in capite died seised of a knight's fee. It was a right to receive of the heir, provided he was of age, one whole year's profits of the lands, if they were in immediate possession; and half a year's profits, if the lands were in reversion expectant on an estate for life.

Primer seisin was a feudal burden, only incident to the king's tenants in capite, and not to those who held of inferior or mesne lords.