Definition of subtend in English:


Line breaks: sub|tend
Pronunciation: /sʌbˈtɛnd


[with object]
  • 1 Geometry (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 angle subtended by a string of length r at the centre of the sphere
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    • The radian is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc.
    • 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.
    • Reticles are in the second focal plane, so as power is changed the angle subtended by the space between lines varies.
  • 1.1(Of an angle or chord) have bounding lines or points that meet or coincide with those of (a line or arc).
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    • 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.
    • 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.
  • 2 Botany (Of a bract) extend under (a flower) so as to support or enfold it: the main beauty is provided by the bracts which subtend the flowers
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    • All flowers are subtended by a bract and two bracteoles.
    • The flower meristems are produced acropetally by the inflorescence meristem and are subtended by bracts.
    • The bract immediately subtends the sepal, partly enclosing it.


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

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