unilateral

adjective

uni·​lat·​er·​al ˌyü-ni-ˈla-tə-rəl 

-ˈla-trəl

1

a

: done or undertaken by one person or party

b

: of, relating to, or affecting one side of a subject : one-sided

c

: constituting or relating to a contract or engagement by which an express obligation to do or forbear is imposed on only one party

2

a

: having parts arranged on one side

a unilateral raceme

b

: occurring on, performed on, or affecting one side of the body or one of its parts

unilateral exophthalmos

3

: unilineal

4

: having only one side

unilaterally adverb

Did you know?

The world is a smaller place than it used to be, and we get uncomfortable when a single nation adopts a policy of unilateralism—that is, acting independently with little regard for what the rest of the world thinks. A unilateral invasion of another country, for instance, usually looks like a grab for power and resources. But occasionally the world welcomes a unilateral action, as when the U.S. announced unilateral nuclear-arms reductions in the early 1990s. Previously, such reductions had only happened as part of bilateral ("two-sided") agreements with the old Soviet Union. Multilateral agreements, on issues such as climate change, often involve most of the world's nations.

Examples of unilateral in a Sentence

Our country is prepared to take unilateral action.

Recent Examples on the Web

Two key developments in particular—the failure of Israel’s unilateral disengagement from Gaza in late 2005 and the collapse of the national unity government and ensuing civil war in Gaza in 2007—effectively doomed his leadership. —Khaled Elgindy, Foreign Affairs, 30 Aug. 2024

All breast cancer patients going in for surgery choose between a lumpectomy, a simpler procedure that only removes the tumor and some surrounding tissues, a single or unilateral mastectomy removing only the affected breast, or a bilateral or double mastectomy. —Angus Chen, STAT, 25 July 2024

The key danger is Trump’s advertised ambition to wield unilateral, unconstrained executive authority even more aggressively than his successor has done. —George F. Will, Washington Post, 15 July 2024

Since the Israel-Gaza war began, it’s been clear that Israeli Prime Minister Benjamin Netanyahu would take unilateral measures, regardless of American advice, to repay Hamas for its ghastly Oct. 7 attack on Israel. —David Ignatius, Washington Post, 31 July 2024

Word History

First Known Use

1802, in the meaning defined at sense 1a

Kids Definition

unilateral

adjective

uni·​lat·​er·​al ˌyü-ni-ˈlat-ə-rəl 

-ˈla-trəl

: done or carried out by only one of two or more parties

unilateral disarmament

unilaterally

-ē

adverb

Medical Definition

unilateral

adjective

uni·​lat·​er·​al ˌyü-ni-ˈlat-ə-rəl, -ˈla-trəl 

: occurring on, performed on, or affecting one side of the body or one of its parts

unilateral exophthalmos

unilaterally

-ē 

adverb

Legal Definition

unilateral

adjective

uni·​lat·​er·​al ˌyü-nə-ˈla-tə-rəl 

1

: done or undertaken by one party

a unilateral mistake as to the terms

2

: of, relating to, or affecting one side of a subject

3

: containing a promise to perform made by only one party especially because the other has already performed (as by paying an amount)

an option contract is unilateral

unilaterally adverb