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

Divisions at Home and Anxiety Abroad A growing chorus of House and Senate Republicans have called out Trump's trade policies and the unilateral way they were implemented. —Raja Krishnamoorthi, MSNBC Newsweek, 9 Apr. 2025

The Trump administration's plans include a unilateral 10% levy that took effect this weekend, as well as steeper tariffs on countries including China, Vietnam and Taiwan — nations that manufacture a significant number of devices and machine components for major U.S. tech companies. —Pia Singh, CNBC, 7 Apr. 2025

Zoom out: In his first term, Trump used provisions of trade laws that allow a president unilateral authority to implement tariffs on specific countries and products on national security grounds, or in retaliation for unfair practices. —Neil Irwin, Axios, 5 Apr. 2025

City council member Brandi Gabbard raised concerns over a unilateral 10% tariff on American imports imposed by the Trump administration. —Jason Clinkscales, Sportico.com, 3 Apr. 2025

Word History

First Known Use

1802, in the meaning defined at sense 1a

Rhymes for unilateral

• basolateral
• contralateral
• dorsolateral
• equilateral
• ipsilateral
• multilateral
• quadrilateral
• ventrolateral
• anterolateral
• posterolateral
• bilateral
• collateral

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