n. pl. u·ni·ties
a. The state or quality of being one or united into a whole: "The Founding Fathers had abhorred the concept of parties, fearing that they would undermine the unity of the nation through factionalism" (Julian E. Zelizer).
b. The state or quality of being in accord; harmony: The judges ruled in unity on the matter.
c. The state or quality of being unified in an aesthetic whole, as in a work of literature: the novel's thematic unity.
d. A whole that is a combination of parts: a group of ideas that taken together constitute a unity.
2. Singleness or constancy of purpose or action; continuity: "In an army you need unity of purpose" (Emmeline Pankhurst).
3. One of the three principles of dramatic structure derived by French neoclassicists from Aristotle's Poetics, stating that a drama should have but one plot, which should take place in a single day and be confined to a single locale.
a. The number 1.
b. See identity element.
[Middle English unite, from Old French, from Latin ūnitās, from ūnus, one; see oi-no- 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.