Definition of subtend in English:



  • 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 angle subtended by a string of length r at the centre of the sphere’
    • ‘The space between the dot and the first letter of the prime to the right of fixation subtended a visual angle of 21.’
    • ‘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.’
    • ‘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.’
    • ‘Reticles are in the second focal plane, so as power is changed the angle subtended by the space between lines varies.’
    • ‘The radian is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc.’
    1. 1.1 (of an angle or chord) have bounding lines or points that meet or coincide with those of (a line or arc).
      • ‘These angles are subtended by the same chord, AW.’
      • ‘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.’
      • ‘This allowed him to calculate the chord subtended by angles of 36, 72, 60, 90 and 120.’
      • ‘Two pairs of parallel sides form equal inscribed angles that are bound to subtend equal chords - the third sides.’
  • 2Botany
    (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’
    • ‘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.’
    • ‘Trillium species are characterized by a single trimerous flower subtended by a whorl of three leaves.’
    • ‘The bract immediately subtends the sepal, partly enclosing it.’
    • ‘A single flower is borne on a scape arising between the basal leaves and subtended by a large, leaf-like bract.’


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