The Collaborative International Dictionary of English v.0.48:

Remissible \Re*mis"si*ble\ (r?-m?s"s?-b'l), a. [L. remissibilis:
   cf. F. r['e]missible. See Remit.]
   Capable of being remitted or forgiven. --Feltham.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "remissible":
   admissible, allowable, condonable, defensible, dispensable,
   excusable, exemptible, expiable, forgivable, inoffensive,
   justifiable, legitimate, pardonable, reasonable, unobjectionable,
   venial, vindicable, warrantable