-ible \-ible\
   see -able.
   1913 webster
see also:
-able 

-able \-able\ -.ab'l. f. -able, l. -abilis.
   an adjective suffix now usually in a passive sense; able to
   be; fit to be; expressing capacity or worthiness in a passive
   sense; as, movable, able to be moved; amendable, able to be
   amended; blamable, fit to be blamed; salable.
   1913 webster

   note: the form -ible is used in the same sense.
         1913 webster

   note: it is difficult to say when we are not to use -able
         instead of -ible. "yet a rule may be laid down as to
         when we are to use it. to all verbs, then, from the
         anglo-saxon, to all based on the uncorrupted
         infinitival stems of latin verbs of the first
         conjugation, and to all substantives, whencesoever
         sprung, we annex -able only." --fitzed. hall.
         1913 webster
see also:
-ible