This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. Uniformity or lack of variation in pitch, intonation, or inflection.

n. Tedious sameness or repetitiousness: the monotony of daily routine.

n. Tedium as a result of repetition or a lack of variety.

n. The property of a monotonic function.

n. The quality of having an unvarying tone or pitch.

n. A frequent recurrence of the same tone or sound, producing a dull uniformity; absence of variety, as in speaking or singing.

n. Any irksome sameness, or want of variety.

n. Uniformity of tone or sound; want of inflections of voice in speaking or reading; want of cadence or modulation; monotone.

n. Tiresome uniformity or lack of variation in any respect; sameness; want of variety.

n. In mathematics:

n. Continual increase, or continual decrease.

n. Unchanging character, neither increasing nor decreasing.

n. the quality of wearisome constancy, routine, and lack of variety

n. constancy of tone or pitch or inflection

"[Sidenote: Monotony] (4) Remember that monotony is the curse of labor for both child and adult, but that _monotony cannot exist where new intellectual insights are constantly being given_."

variety   

unvariedness    stability    constancy   

monotonous    monotone   

monotone    sameness    sameliness    humdrum    dreariness    drearihead    dreariment    drearihood   

botany    neoteny    paleobotany   

drudgery    loneliness    boredom    solitude    desolation    hardship    stillness    uniformity    toil    misery