IPA: /məˈnɒtənɪkli/
KK: /mənɑːtəˈnɪkli/
In a way that is consistently increasing or decreasing without any change in direction.
The function behaves monotonically, meaning it either only increases or only decreases as the input changes.
Monotonically → It is formed from "mono-" (from Greek "monos", meaning single or alone) and "tonos" (meaning tone or tension) combined with the suffix "-ically" (meaning in a manner). The word "monotonically" refers to a manner of change that is consistent and unchanging in tone or direction, typically in mathematics or functions.
Think of 'single' ('mono-') and 'tone' ('tonos') to remember that 'monotonically' describes a consistent and unchanging manner.