The Collaborative International Dictionary of English v.0.48:

Oyer \O"yer\, n. [Anglo F., a hearing, from OF. o["i]r, F.
   ou["i]r, to hear, L. audire. See Audible.] (Law)
   A hearing or an inspection, as of a deed, bond, etc., as when
   a defendant in court prays oyer of a writing. --Blackstone.
   [1913 Webster]

   Oyer and terminer (Law), a term used in England in
      commissions directed to judges of assize about to hold
      court, directing them to hear and determine cases brought
      before them. In the U.S. the phrase is used to designate
      certain criminal courts.
      [1913 Webster]