to extend between the end points of the lines that converge to form (an angle)
A hypotenuse subtends a right angle
to extend between the end points of (an arc)
an arc subtended by a chord
said of a plant part: to be lower than (something), esp so as to embrace or enclose it
a bract that subtends a flower
[Latin subtendere to stretch beneath, from sub- + tendere to stretch]