monotone
/ˈmɒ.nə.təʊn/
noun
Meaning
A single unvaried tone of speech or a sound.
"When Tima felt like her parents were treating her like a servant, she would speak in monotone and act as though she were a robot."
A piece of writing in one strain throughout.
verb
Meaning
To speak in a monotone.
adjective
Meaning
(of speech or a sound) Having a single unvaried pitch.
Being, or having the salient properties of, a monotone function.
"The function f(x):=x^3 is monotone on \R, while g(x):=x^2 is not."