bilateral

1 of 2

adjective

bi·​lat·​er·​al (ˌ)bī-ˈla-t(ə-)rəl 

1

: affecting reciprocally two nations or parties

a bilateral treaty

a bilateral trade agreement

2

: having two sides

dealing with a bilateral problem

3

biology

a

: of, relating to, or affecting the right and left sides of the body or the right and left members of paired organs

bilateral nephrectomy

b

: having bilateral symmetry

bilateralism

(ˌ)bī-ˈla-t(ə-)rə-ˌli-zəm 

noun

bilaterally adverb

bilateralism

2 of 2

noun

bi·​lat·​er·​al·​ism (ˌ)bī-ˈla-t(ə-)rə-ˌli-zəm 

plural -s

1

: the state of being bilateral

especially : bilateral symmetry

2

: the practice of advancing trade between two countries by concluding agreements governing such factors as the volume and composition of trade, the price of commodities, and the settling of accounts

—contrasted with multilateralism

Did you know?

Since the prefix bi- means "two" in Latin, bilateral means essentially "two-sided". In the days when there were two superpowers, the U.S. and the Soviet Union regularly engaged in bilateral arms negotiations; such negotiations are much less common today. Sometimes bilateral refers to two sides of the same thing. A bilateral hip replacement, for instance, replaces both hip bones in the same operation. And bilateral symmetry (a term often used by biologists) refers to the fact that, in many organisms (such as humans), the left side is basically the mirror image of the right side.

Examples of bilateral in a Sentence

Recent Examples on the Web

Adjective

Marcos held a bilateral meeting with Putin on the sidelines of the summit in Kazan. — CBS News, 20 June 2026

China’s recent decision to scrap tariffs on African imports led to an 18% jump in bilateral trade, a surge that comes as both China and the US vie for influence on the continent, especially in terms of control of Africa’s key mineral resources. — Jeronimo Gonzalez, semafor.com, 19 June 2026

Then on Wednesday, the two held a bilateral meeting. — Kyra Colah, FOXNews.com, 18 June 2026

Another bilateral meeting on the sidelines of the summit was with Turkey's Foreign Minister Hakan Fidan, who met in Moscow on Tuesday with his Russian counterpart Sergey Lavrov. — ABC News, 17 June 2026

Word History

First Known Use

Adjective

1751, in the meaning defined at sense 1

Phrases Containing bilateral

• bilateral symmetry

Rhymes for bilateral

• collateral
• trilateral
• anterolateral
• posterolateral
• basolateral
• contralateral
• dorsolateral
• equilateral
• ipsilateral
• multilateral
• quadrilateral
• unilateral

Kids Definition

bilateral

adjective

bi·​lat·​er·​al (ˈ)bī-ˈlat-ə-rəl 

-ˈla-trəl

1

: having or involving two sides or parties

a bilateral treaty

2

: characterized by bilateral symmetry

bilaterally

-ē

adverb

Medical Definition

bilateral

adjective

bi·​lat·​er·​al (ˈ)bī-ˈlat-ə-rəl, -ˈla-trəl 

1

: of, relating to, or affecting the right and left sides of the body or the right and left members of paired organs

bilateral nephrectomy

bilateral tumors of the adrenal glands

2

: having bilateral symmetry

bilateralism

-ˌiz-əm 

noun

bilaterality

(ˈ)bī-ˌlat-ə-ˈral-ət-ē, -ˌla-ˈtral- 

noun

plural bilateralities

bilaterally

(ˈ)bī-ˈlat-ə-rə-lē, -ˈla-trə-lē 

adverb

Legal Definition

bilateral

adjective

bi·​lat·​er·​al ˌbī-ˈla-tə-rəl 

: affecting, obligating, or shared by both parties

bilaterally

-rə-lē

adverb