n. pl. spec·u·la (-lə) or spec·u·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.
a. A bright, often iridescent patch of color on the wings of certain birds, especially ducks.
b. A transparent spot in the wings of some butterflies or moths.
[Middle English, surgical speculum, from Latin, mirror, from specere, to look at; see spek- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.