continuing without interruption; ceaseless; unending: an incessant noise.
Origin: 1425–75; late Middle English incessaunte < Late Latin incessant-, equivalent to Latin in-in-3 + cessant- (stem of cessāns), present participle of cessāre to stop work; see cease, -ant
1461 (implied in incessantly), from O.Fr. incessant (1358), from L.L. incessantem (nom. incessans) "unceasing," from L. in- "not" + cessantem (nom. cessans), prp. of cessare "cease."