Definition of "unit"

unit

/ˈjuː.nɪt/

noun
plural units
1. (mathematics) Oneness, singularity, seen as a component of a whole number; a magnitude of one.
  Quotations
  Number, we define, to be, a certayne Mathematicall Sũme, of Vnits. [Note the worde, Vnit, to expresse the Greke Monas, & not Vnitie: as we haue all, commonly, till now, vsed.]
  1570, John Dee, in H. Billingsley (trans.) Euclid, Elements of Geometry, Preface
2. (sciences) A standard measure of a quantity.
3. The number one.
4. Ellipsis of international unit.
5. An organized group comprising people and/or equipment.
6. (military, informal) A member of a military organization.
7. (commerce) An item which may be sold singly.
8. (US, UK, Australia, New Zealand) any piece of equipment, such as an appliance, power tool, stereo system, computer, tractor, or machinery.
9. (US, Australia, New Zealand) a measure of housing equivalent to the living quarters of one household; an apartment where a group of apartments is contained in one or more multi-storied buildings or a group of dwellings is in one or more single storey buildings, usually arranged around a driveway.
10. (medicine) A quantity of approximately 517 milliliters (1.1 U.S. pints) of blood.
11. (US, military) Any military element whose structure is prescribed by competent authority, such as a table of organization and equipment; specifically, part of an organization.
12. (US, military) An organization title of a subdivision of a group in a task force.
13. (US, military) A standard or basic quantity into which an item of supply is divided, issued, or detailed. In this meaning, also called unit of issue.
14. (US, military) With regard to Reserve Components of the Armed Forces, denotes a Selected Reserve unit organized, equipped, and trained for mobilization to serve on active duty as a unit or to augment or be augmented by another unit. Headquarters and support functions without wartime missions are not considered units.
15. (algebra) The identity element, neutral element.
  Quotations
  An element 𝑒 of 𝑆 such that 𝑒𝑥 = 𝑥 = 𝑥𝑒 for all 𝑥 ∈ 𝑆 is called a unit element. (When the law of composition is written additively, the unit element is denoted by 0, and is called a zero element.)
  2005, Serge Lang, Algebra, 3rd edition, Springer, page 3
16. (algebra) An element having an inverse, an invertible element; an associate of the unity.
  Quotations
  Let 𝐴 be an arbitrary integral domain. We say that an element 𝑎 ∈ 𝐴 is invertible or is a unit of 𝐴 if it has an inverse in 𝐴; in ℤ the units are ±1, […]
  1990, A. I. Kostrikin, I. R. Shafarevich, editors, Algebra I, Springer, page 22
17. (category theory) In an adjunction, a natural transformation from the identity functor of the domain of the left adjoint functor to the composition of the right adjoint functor with the left adjoint functor.
18. (geology) A volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it.
  Quotations
  For example, the Moenkopi Formation was named for the small settlement of Moenkopi, Arizona where the formation was first defined as being a separate unit from the rocks above and beneath it.
  2012, Chinle Miller, In Mesozoic Lands: The Mesozoic Geology of Arches and Canyonlands National Parks, Kindle edition
19. (UK) A unit of alcohol.
20. (UK, electricity) One kilowatt-hour (as recorded on an electricity meter).
21. (historical) A gold coin of the reign of James I, worth twenty shillings.
22. A work unit.
23. (UK, Australia, slang) A physically large person.
  Quotations
  Luca's father, Americo Campanaro, said: "I feel like my heart has been ripped out."Mr Campanaro added: "He was a big lad, a big unit, that's why he was a goalkeeper, with a big heart to match. A gentle giant."
  2018 December 11, “Aylesbury goalkeeper, 14, dies after match injury”, in BBC News
24. (US, slang, vulgar) A penis, especially a large one.
adjective
not comparable
1. For each unit.
2. (mathematics) Having a size or magnitude of one.
  Quotations
  Consider the following time sequence Z t = A sin ⁡ ( ω t + θ ) {\displaystyle Z_{t}=A\sin(\omega t+\theta )} , / where A {\displaystyle A} is a random variable with a zero mean and a unit variance and θ {\displaystyle \theta } is a random variable with a uniform distribution on the interval [ − π , π ] {\displaystyle [-\pi ,\pi ]} independent of A {\displaystyle A} .
  1990, William W. S. Wei, Time Series Analysis, page 9