The Collaborative International Dictionary of English v.0.48:

Sufferable \Suf"fer*a*ble\, a. [Cf. F. souffrable.]
   1. Able to suffer or endure; patient. [Obs.] "Ye must be
      sufferable." --Chaucer.
      [1913 Webster]

   2. That may be suffered, tolerated, or permitted; allowable;
      tolerable.
      [1913 Webster] -- Suf"fer*a*ble*ness, n. --
      Suf"fer*a*bly, adv.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sufferable
    adj 1: capable of being borne though unpleasant; "sufferable
           punishment" [syn: bearable, endurable, sufferable,
           supportable]