n. pl. rhom·bus·esor rhom·bi (-bī)
An equilateral parallelogram, especially one having oblique angles. Also called rhomb.
[Late Latin, from Greek rhombos, bullroarer, lozenge-shaped flatfish, rhombus (a rhombus being so called in reference to lozenge-shaped wooden slat of a bullroarer), from rhembesthai, to roll about, go round and round; see wer-2 in the Appendix of Indo-European roots.]
(click for a larger image)rhombus
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.