Hi !!
I guess you mean "stretch"
It depends .....
If it's to stretch = étirer
you stretch your muscles after exercising = étirer ses muscles
if it's the adjective = étirable, extensible
we use the word "stretch" in France for the jeans very tight. they put stretch material to make them more comfortable...stretch jeans
so that would be "extensible" except that we say "stretch" !!!
or faire du stretching = faire des étirements = have a stretch class
It depends on the context
Has other meanings as well as ....it would be easier to translate in a sentence....
a stretch of sand, water = étendue
a small stretch of road = une portion de route
stretch marks = vergétures
.......
Hope this will help :)