The Collaborative International Dictionary of English v.0.48:

Resolvent \Re*solv"ent\ (-ent), a.
   Having power to resolve; causing solution; solvent.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Resolvent \Re*solv"ent\, n. [L. resolvens, p. pr. of resolvere:
   cf. F. r['e]solvant. See Resolve.]
   1. That which has the power of resolving, or causing
      solution; a solvent.
      [1913 Webster]

   2. (Med.) That which has power to disperse inflammatory or
      other tumors; a discutient; anything which aids the
      absorption of effused products. --Coxe.
      [1913 Webster]

   3. (Math.) An equation upon whose solution the solution of a
      given pproblem depends.
      [1913 Webster]

WordNet (r) 3.0 (2006):

resolvent
    n 1: a liquid substance capable of dissolving other substances;
         "the solvent does not change its state in forming a
         solution" [syn: solvent, dissolvent, dissolver,
         dissolving agent, resolvent]