Main Entry: sub·tend

Pronunciation: \səb-ˈtend\

Function: transitive verb

Etymology: Latin subtendere to stretch beneath, from sub- + tendere to stretch — more at thin

Date: 1570

1 a : to be opposite to and extend from one side to the other of <a hypotenuse subtends a right angle> b : to fix the angular extent of with respect to a fixed point or object taken as the vertex <a central angle subtended by an arc> <the angle subtended at the eye by an object of given width and a fixed distance away> c : to determine the measure of by marking off the endpoints of <a chord subtends an arc>
2 a : to underlie so as to include b : to occupy an adjacent and usually lower position to and often so as to embrace or enclose <a bract that subtends a flower>