Webster's Revised Unabridged Dictionary · 1913

Monotony

Monotony , noun

[Greek {not transcribed}: compare French monotonie. See Monotonius.]

1.
A frequent recurrence of the same tone or sound, producing a dull uniformity; absence of variety, as in speaking or singing.
2.
Any irksome sameness, or want of variety.
At sea, everything that breaks the monotony of the surrounding expanse attracts attention. — W. Irving