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diopter - 5 dictionary results

di⋅op⋅ter

  [dahy-op-ter]
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–noun
1. Optics. a unit of measure of the refractive power of a lens, having the dimension of the reciprocal of length and a unit equal to the reciprocal of one meter. Abbreviation: D
2. an instrument, invented by Hipparchus, to measure the apparent diameter of the sun or moon or to estimate the size or elevation of distant objects.
Also, especially British, di⋅op⋅tre.

Origin:
1585–95; < L dioptra < Gk: instrument for measuring height or levels, equiv. to di- di- 3 + op- (for ópsesthai to see) + -tra n. suffix of means

Related forms:
di⋅op⋅tral, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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di·op·ter   (dī-ŏp'tər)   
n.   Abbr. D.
A unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length measured in meters.

[Obsolete diopter, an instrument for measuring angles, from Latin dioptra, from Greek dioptrā : dia-, dia- + optos, visible; see okw- in Indo-European roots.]
di·op'tral (-trəl) adj.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Diopter

Di*op"ter\, Dioptra \Di*op"tra\, n. [L. dioptra, fr. Gr. ?. See 2d Dioptric.] An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc.
Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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Main Entry: di·op·ter
Variant: or chiefly British di·op·tre /dI-'äp-t&r, 'dI-"äp-/
Function: noun
: a unit of measurement of the refractive power of a lens equal to the reciprocal of the focal length in meters
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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diopter di·op·ter (dī-ŏp'tər)
n.
Abbr. D.
A unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length measured in meters.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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