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bilateral

by-LAT-uhr-uhl /ˌbaɪˈlætərəl/

adjectiveC1GREGMATIELTS

academicformal

Having or relating to two sides; affecting both sides equally. In anthropology, tracing descent through both the mother's and father's lines.

In daily life, bilateral refers to two-sided agreements (like trade deals). In anthropology, it describes how modern Westerners trace their family tree—valuing both maternal and paternal relatives equally.

The story behind the word. From the Latin bis (twice) and latus (side). It entered English in the 18th century to describe things with two symmetrical sides, and was later adopted by diplomats and social scientists.

Word relationships

two-sided: Two-sided is a casual, physical description, whereas bilateral is formal, legal, and structural.
cognatic: Cognatic is a technical anthropological synonym for bilateral descent.

unilateral: Unilateral means affecting or performed by only one side.
multilateral: Multilateral involves more than two sides or nations.

Commonly confused with

ambilineal: Ambilineal allows an individual to choose to affiliate with either the mother's or father's line, whereas bilateral automatically includes both lines simultaneously.

Word family

bilaterally (adverb): In a way that affects or involves two sides.

Collocations

bilateral agreement
bilateral descent
bilateral talks
bilateral relations

Example sentences

"The two nations signed a bilateral trade agreement to reduce tariffs on agricultural goods." Discussing international diplomacy.
"Most modern industrial societies practice bilateral descent, meaning children consider themselves equally related to both parents' families." An anthropological description of Western family structures.

Memory hook

The prefix 'bi-' means two (like a bicycle with two wheels). 'Lateral' means side (like a lateral pass in football). Two sides! Bi- (two) + lateral (sides) = affecting both sides.

When not to use

Do not use when referring to a decision made by only one party (which is unilateral) or multiple parties (multilateral).

Fun facts

While bilateral descent seems natural to Westerners, it is actually historically rare; most agricultural civilizations preferred patrilineal systems to keep land intact under one male head.