bilateral

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

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

His trip, scheduled for Dec. 2 through Dec. 4, will begin with a bilateral meeting with Angolan President João Lourenço in the capital of Luanda, according to a senior administration official previewing the trip. —Justin Gomez, ABC News, 1 Dec. 2024

Taiwan is one of the main sources of tension in the bilateral relationship. —Taijing Wu, arkansasonline.com, 1 Dec. 2024

Last week, a 39-year-old from Washington state, who did not want to be named, underwent a bilateral salpingectomy, in which her fallopian tubes were removed. —Thomas G. Moukawsher, Newsweek, 30 Nov. 2024

Nick Bosa believes is the best back in the NFL. McCaffrey, felled by bilateral Achilles tendinitis for the first eight games of the season, has gone right back into the lineup with his usual workload a year after rushing for 1,459 yards, catching 56 passes for 564 more. —Jerry McDonald, The Mercury News, 29 Nov. 2024

Word History

First Known Use

1751, in the meaning defined at sense 1

Phrases Containing bilateral

• bilateral symmetry

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