subtend
Meaning
(of a line, arc, or figure) to form (an angle) at a particular point when straight lines from its extremities are joined at that point.
(in botany) (of a bract or leaf) to extend under or be opposite to (a flower or fruit).
Structure
Usage
The chord subtends an angle of 60 degrees at the center of the circle.
In this species, a large bract subtends each individual flower.
To find the arc length, you must first identify the angle it subtends.
Etymology
The word "subtend" is a direct borrowing from the Latin subtendere, which is a compound of sub- ("under") and tendere ("to stretch"). The literal image is of a line stretching under an arc or angle. This geometric concept was adopted into English in the late 16th century, preserving the core Latin meaning. The botanical sense, where a leaf or bract "stretches under" a flower, developed as a direct metaphorical extension of this geometric principle.
Analysis
sub is a Latin prefix meaning "under, below, from beneath." tend is from the Latin verb tendere, meaning "to stretch, extend, or aim."