# Definition of subtend in US English:

## subtend

### verb

[with object]
• 1Geometry
(of a line, arc, or figure) form (an angle) at a particular point when straight lines from its extremities are joined at that point.

• ‘The space between the dot and the first letter of the prime to the right of fixation subtended a visual angle of 21.’
• ‘The radian is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc.’
• ‘Reticles are in the second focal plane, so as power is changed the angle subtended by the space between lines varies.’
• ‘In other words, when two plates subtended the same angle - one big and far away, the other small and nearby - the antennae also made the same angle with each other.’
• ‘The most common geometry for curved crystal diffraction is based on the Rowland circle principle, which relies on the well-known property of a circle that an arc segment subtends a constant angle for any point on the circle.’
1. 1.1 (of an angle or chord) have bounding lines or points that meet or coincide with those of (a line or arc).
• ‘Two pairs of parallel sides form equal inscribed angles that are bound to subtend equal chords - the third sides.’
• ‘This allowed him to calculate the chord subtended by angles of 36, 72, 60, 90 and 120.’
• ‘The Arc, Chord, Radius, Height, Angle, Apothem, and Area Suppose you have a segment of a circle, bounded by an arc of the circle and the chord subtending it.’
• ‘These angles are subtended by the same chord, AW.’
• ‘In fact Shen demonstrated a remarkable ability to view spatial arrangements and he gave an approximate formula for the length of a circular arc in terms of the chord subtending the arc.’
• 2Botany
(of a bract) extend under (a flower) so as to support or enfold it.

• ‘All flowers are subtended by a bract and two bracteoles.’
• ‘The bract immediately subtends the sepal, partly enclosing it.’
• ‘The flower meristems are produced acropetally by the inflorescence meristem and are subtended by bracts.’
• ‘Trillium species are characterized by a single trimerous flower subtended by a whorl of three leaves.’
• ‘A single flower is borne on a scape arising between the basal leaves and subtended by a large, leaf-like bract.’

### Origin

Late 16th century (in subtend (sense 1)): from Latin subtendere, from sub- ‘under’ + tendere ‘stretch’. subtend (sense 2) dates from the late 19th century.

## subtend

/səbˈtɛnd//səbˈtend/