spec·u·lum (spĕk'yə-ləm)
n., pl., -la (-lə), or -lums.

1. A mirror or polished metal plate used as a reflector in optical instruments.
2. An instrument for dilating the opening of a body cavity for medical examination.
3. Zoology.
   1. A bright, often iridescent patch of color on the wings of certain birds, especially ducks.
   2. A transparent spot in the wings of some butterflies or moths.

[Middle English, surgical speculum, from Latin, mirror, from specere, to look at.]

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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