Source : Webster's Revised Unabridged Dictionary (1913)

Incessant \In*ces"sant\, a. [L. incessans, -antis; pref. in- not
   + cessare to cease: cf. F. incessant. See {Cease}.]
   Continuing or following without interruption; unceasing;
   unitermitted; uninterrupted; continual; as, incessant
   clamors; incessant pain, etc.

         Against the castle gate, . . . Which with incessant
         force and endless hate, They batter'd day and night and
         entrance did await.                      --Spenser.

   Syn: Unceasing; uninterrupted; unintermitted; unremitting;
        ceaseless; continual; constant; perpetual.

Source : WordNet®

incessant
     adj 1: occurring so frequently as to seem ceaseless or
            uninterrupted; "a child's incessant questions"; "your
            perpetual (or continual) complaints" [syn: {perpetual},
             {endless}]
     2: uninterrupted in time and indefinitely long continuing; "the
        ceaseless thunder of surf"; "in constant pain"; "night and
        day we live with the incessant noise of the city"; "the
        never-ending search for happiness"; "the perpetual
        struggle to maintain standards in a democracy"; "man's
        unceasing warfare with drought and isolation";
        "unremitting demands of hunger" [syn: {ceaseless}, {constant},
         {never-ending}, {perpetual}, {unceasing}, {unremitting}]