Source : Webster's Revised Unabridged Dictionary (1913)

Unlike \Un*like"\, a.
   1. Not like; dissimilar; diverse; having no resemblance; as,
      the cases are unlike.

   2. Not likely; improbable; unlikely. [Obsoles.]

   {Unlike quantities} (Math.), quantities expressed by letters
      which are different or of different powers, as a, b, c,
      a^{2}, a^{3}, x^{n}, and the like.

   {Unlike signs} (Math.), the signs plus (+) and minus (-).