Webster’s Revised Unabridged Dictionary · 1913
Monotonous
Mo·not′o·nous (·nŭs), a. [Gr. ?; μόνος alone, single + τόνος tone. See Tone.] Uttered in one unvarying tone; continued with dull uniformity; characterized by monotony; without change or variety; wearisome. — Mo·not′o·nous·ly, adv. — Mo·not′o·nous·ness, n.