The Collaborative International Dictionary of English v.0.48:

Ratifier \Rat"i*fi`er\ (r[a^]t"[i^]*f[imac]`[~e]r), n.
   One who, or that which, ratifies; a confirmer. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ratifier
    n 1: someone who expresses strong approval [syn: subscriber,
         endorser, indorser, ratifier]