Part of speech: Adjective (satellite)
uninterrupted in time and indefinitely long continuing
Example: 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
Constant, Unremitting, Incessant, Ceaseless, Perpetual
The word "incessant" comes from Old French incessant.
Many English words entered through French but originally came from Latin, Arabic, or even Persian.