1. Characterized by or consisting of two parts or components; twofold.
a. Of or relating to a system of numeration having 2 as its base.
b. Of or relating to a system of encoding data using only 0's and 1's.
3. Chemistry Consisting of or containing only two kinds of atoms.
4. Of or employing two comparatively nontoxic chemicals that combine to produce a deadly poison: binary weapons; a binary nerve agent.
5. Music Having two sections or subjects.
n. pl. bi·na·ries
1. A number system having 2 as its base.
2. A file that contains the executable version of a computer program.
3. A binary star.
[Middle English binarie, from Late Latin bīnārius, from Latin bīnī, two by two; see dwo- 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.