Source : Webster's Revised Unabridged Dictionary (1913)

Continual \Con*tin"u*al\, a. [OE. continuel, F. continuel. See
   {Continue}.]
   1. Proceeding without interruption or cesstaion; continuous;
      unceasing; lasting; abiding.

            He that is of a merry heart hath a continual feast.
                                                  --Prov. xv.
                                                  15.

   2. Occuring in steady and rapid succession; very frequent;
      often repeated.

            The eye is deligh by a continental succession of
            small landscapes.                     --W. Irwing.

   {Continual proportionals} (Math.), quantities in continued
      proportion. --Brande & C.

   Syn: Constant; prepetual; incessant; unceasing;
        uninterrupted; unintermitted; continuous. See
        {Constant}, and {Continuous}.

Source : WordNet®

continual
     adj 1: seemingly without interruption; chiefly restricted to what
            recurs regularly or frequently in a prolonged and
            closely spaced series; "the continual banging of the
            shutters" [ant: {sporadic}]
     2: `continual' (meaning seemingly uninterrupted) is often used
        interchangeably with `continuous' (meaning without
        interruption)