Reflex

Origin

From Late Latin reflexus, past participle of reflectere ("to bend back"). Photography sense is from noun sense meaning “reflection”.

Full definition of reflex

Noun

1. An automatic response to a simple stimulus which does not require mental processing.
• 2012, May 5, Phil McNulty, Chelsea 2-1 Liverpool, He met Luis Suarez's cross at the far post, only for Chelsea keeper Petr Cech to show brilliant reflexes to deflect his header on to the bar. Carroll turned away to lead Liverpool's insistent protests that the ball had crossed the line but referee Phil Dowd and assistant referee Andrew Garratt waved play on, with even a succession of replays proving inconclusive.
2. (linguistics) the descendant of an earlier language element, such as a word or phoneme, in a daughter language
3. (obsolete) Reflection; the light reflected from an illuminated surface to one in shade.
• ShakespeareYon gray is not the morning's eye,
  'Tis but the pale reflex of Cynthia's brow.
• TennysonOn the depths of death there swims
  The reflex of a human face.

Adjective

1. Bent, turned back or reflected.
• Sir M. Halethe reflex act of the soul, or the turning of the intellectual eye inward upon its own actions
2. Produced automatically by a stimulus.
3. (geometry, of an angle) Having greater than 180 degrees but less than 360 degrees.
• 1878, James Maurice Wilson, Elementary Geometry, MacMillan, page 10:A polygon is said to be convex when no one of its angles is reflex.
• 1895, David Eugen Smith and Wooster Woodruff Bernan, New Plane and Solid Geometry, page 7:An angle less than a right angle is said to be acute; one greater than a right angle but less than a straight angle is said to be obtuse; one greater than a straight angle but less than a perigon is said to be reflex or convex.
• 1958, Howard Fehr, “On Teaching Dihedral Angle and Steradian” in The Mathematics Teacher, v 51, National Council of Teachers of Mathematics, page 275:If the reflex region is the interior of the angle, the dihedral angle is reflex.
• 1991, B. Falcidieno et al, “Configurable Representations in Feature-based Modelling” in Eurographics '91: Proceedings, North-Holland, page 145:A reflex edge of a polyhedron is an edge where the inner dihedral angle subtended by two incident faces is greater than 180°.
• 2001, Esther M. Arkin et al, “On the Reflexivity of Point Sets”, in Algorithms and data structures: 7th International Workshop, WADS 2001: Proceedings, Springer, page 195:We say that an angle is convex if it is not reflex.
• 2004, Ana Paula Tomás and António Leslie Bajuelos, “Quadratic-Time Linear-Space Algorithms Generating Orthogonal Polygons with a Given Number of Vertices”, in Computational Science and Its Applications – ICCSA 2004 Proceedings, part 3, Springer, page 117:P denotes a polygon and r the number of reflex vertices.
4. (photography) Of a camera or camera mechanism, using a mirror to reflect the image onto a ground-glass viewfinder, allowing the photographer to see it up to the moment of exposure.

Synonyms

• (of an angle) re-entrant

Descendants

• reflex camera
• reflex mirror
• reflex viewfinder
• single-lens reflex, single lens reflex, SLR
• twin-lens reflex, twin lens reflex, TLR, dual-lens reflex

Verb

1. to bend, turn back or reflect
2. to respond to a stimulus----