bra·chi·um (brākē-əm, brăkē-)
n. pl. bra·chi·a (brākē-ə, brăkē-ə)
1. The part of the upper arm or forelimb extending from the shoulder to the elbow.
2. An arm or a homologous anatomical structure, such as a flipper or wing.
3. The part of a limb or process corresponding to an arm.
[Latin brācchium, arm, from Greek brakhīōn, upper arm; see mregh-u- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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.