Dualities

Part of speech: noun

Definitions

1. The quality of existing in two contrasting states simultaneously
2. The condition of embodying two different or opposing features at once
3. A situation where two separate qualities or principles coexist within a single entity

Etymology: "Dualities" is the plural of "duality," so its history is that of the singular noun. That noun comes from Latin "duālitās," which is built from "dual" plus the suffix "-ity." "Dual" itself goes back to Latin "duo," meaning "two," so the core of the word is simply the idea of twoness. The suffix "-ity" is the familiar Latin-derived ending that turns an adjective into a noun for a quality or state, as in "clarity" from "clear" or "rarity" from "rare." The result is a word that names the condition of being two-fold rather than a thing that is two. Its meaning of holding two contrasting states at once grows from that sense of paired, opposite aspects, which is why the plural form is used for several such pairings at once.