Sentence:  Thus if e is sufficiently small , there can be only one intersection of C and **f near Q , for if there were more than one intersection for every e then the difference between C and **f near Q would not be a <WSD>monotone</WSD> function . 
Meaning of the word marked with <WSD> tags:  of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value