The Collaborative International Dictionary of English v.0.48:
Primer \Prim"er\, a. [OF. primer, primier, premier, F. premier.
First; original; primary. [Obs.] "The primer English kings."
Primer fine (O. Eng. Law), a fine due to the king on the
writ or commencement of a suit by fine. --Blackstone.
Primer seizin (Feudal Law), the right of the king, when a
tenant in capite died seized of a knight's fee, to receive
of the heir, if of full age, one year's profits of the
land if in possession, and half a year's profits if the
land was in reversion expectant on an estate for life; --
now abolished. --Blackstone.