Source : Webster's Revised Unabridged Dictionary (1913)

Inadvisable \In`ad*vis"a*ble\, a.
   Not advisable. -- {In`ad*vis"a*ble*ness}, n.

Source : WordNet®

inadvisable
     adj 1: not prudent or wise; not recommended; "running on the ice is
            inadvisable" [syn: {unadvisable}] [ant: {advisable}]
     2: not advisable; "an unnecessary and inadvisable action"