subtend

verb

Etymology: From Latin subtendere, from sub (“under”) + tendere (“to stretch, extend”), itself a semantic loan from Ancient Greek ὑποτείνω (hupoteínō, “to subtend”), from which hypotenuse also derives. See tend.

1. To use an angle to delimit (mark off, enclose) part of a straight or curved line, for example an arc or the opposite side of a triangle.

   “A 43° angle subtends an arc of about 0.75 meters on a circle with a radius of 1 meter.”

2. To extend or stretch opposite something; to be part of a straight or curved line that is opposite to and delimits an angle.

   “A hypotenuse subtends the right angle of a right triangle.”

   “An arc measuring about 0.75 meters on a circle with a radius of 1 meter subtends an angle of about 43°.”

3. To form the central angle of a circle underneath an arc.

   “The points A and B on the circumference form the arc AB, which subtends the central angle θ.”

4. To stand beneath or close to, as a bract at the base of a flower.