monotonic function
nounUK /ˌmɒnəˈtɒnɪk ˈfʌŋkʃən/
US /ˌmɑːnəˈtɑːnɪk ˈfʌŋkʃən/
A monotonic function is a math rule that always goes one way, never turning back.
The function f(x) = 2x is monotonic because it keeps going up as x gets bigger.
OTHER MEANINGS
2. A function that never decreases as its input increases.
A monotonic increasing function like f(x) = x + 3 always rises.
3. A function that never increases as its input increases.
A monotonic decreasing function like f(x) = -x always falls.
4. A function that stays the same or moves in only one direction.
The step function is monotonic because it never goes down.