The Collaborative International Dictionary of English v.0.48:

Primer \Prim"er\, n. [Originally, the book read at prime, the
   first canonical hour. LL. primae liber. See Prime, n., 4.]
   1. Originally, a small prayer book for church service,
      containing the little office of the Virgin Mary; also, a
      work of elementary religious instruction.
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            The primer, or office of the Blessed Virgin. --Bp.
                                                  Stillingfleet.
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   2. A small elementary book for teaching children to read; a
      reading or spelling book for a beginner.
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            As he sat in the school at his prymer. --Chaucer.
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   3. (Print.) A kind of type, of which there are two species;
      one, called long primer, intermediate in size between
      bourgeois and small pica [see Long primer]; the other,
      called great primer, larger than pica.
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   Note: Great primer type.
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The Collaborative International Dictionary of English v.0.48:

Primer \Prim"er\, n.
   One who, or that which, primes; specifically, an instrument
   or device for priming; esp., a cap, tube, or water containing
   percussion powder or other compound for igniting a charge of
   gunpowder.
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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.
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   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]

WordNet (r) 3.0 (2006):

primer
    n 1: an introductory textbook
    2: any igniter that is used to initiate the burning of a
       propellant [syn: fuse, fuze, fusee, fuzee, primer,
       priming]
    3: the first or preliminary coat of paint or size applied to a
       surface [syn: flat coat, ground, primer, priming,
       primer coat, priming coat, undercoat]