Where does “durative” come from?

Durative comes from Old French duratif, meaning continuing or lasting in duration.

durative (English): Of or pertaining to duration; Long-lasting; Of or...

Definitions

Step	Language	Word	Meaning
1	French	duratif	durative; the durative case
2	Old French	durer	to last
3	Latin	dūrō	—
4	Latin	dūrus	—
5	Proto-Italic	dūros	—
6	Proto-Indo-European	duh₂-ró-s	long, far
7	Proto-Indo-European	dweh₂-	far; long

durative — Etymology, Origin & Word History | Etymology Explorer