The Collaborative International Dictionary of English v.0.48:

Primer \Prim"er\, a. [OF. primer, primier, premier, F. premier.
   See Premier.]
   First; original; primary. [Obs.] "The primer English kings."
   --Drayton.
   [1913 Webster]

   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.
      [1913 Webster]