The Collaborative International Dictionary of English v.0.48:

Peerage \Peer"age\, n. [See Peer an equal, and cf. Parage.]
   1. The rank or dignity of a peer. --Blackstone.
      [1913 Webster]

   2. The body of peers; the nobility, collectively.
      [1913 Webster]

            When Charlemain with all his peerage fell. --Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

peerage
    n 1: the peers of a kingdom considered as a group [syn:
         peerage, baronage]