Noun

(uncountable) Oneness; the state or fact of being one undivided entity.

* 1846 ,

If any literary work is too long to be read at one sitting, we must be content to dispense with the immensely important effect derivable from unity of impression - for, if two sittings be required, the affairs of the world interfere, and everything like totality is at once destroyed.

* {{quote-news

, year=2011 , date=October 1 , author=Saj Chowdhury , title=Wolverhampton 1 - 2 Newcastle , work=BBC Sport citation , page= , passage=Alan Pardew's current squad has been put together with a relatively low budget but the resolve and unity within the team is priceless.}}

A single undivided thing, seen as complete in itself.

* 1999 , Joyce Crick, translating Sigmund Freud, The Interpretation of Dreams , Oxford 2008, p. 137:

If a single day has brought us two or more experiences suitable to initiate a dream, the dream will unite references to them both into a single whole; it obeys a compulsion to form a unity out of them .

(drama) Any of the three classical rules of drama (unity of action, unity of place, and unity of time).`

(mathematics) Any element of a set or field that behaves under a given operation as the number 1 behaves under multiplication.

(legal) The peculiar characteristics of an estate held by several in joint tenancy.

Noun

(Root of unity) (-)

(mathematics) The branch of mathematics concerned with the complex roots of unity; cyclotomy