missing link

American  

[mis-ing lingk] / ˈmɪs ɪŋ ˈlɪŋk /

noun

1. a hypothetical form of animal assumed to have constituted a connecting link between the anthropoid apes and humans, identified by some authorities as constituting the genus Australopithecus.

2. something lacking for the completion of a series or sequence.

   It’s tricky to find the missing link between children’s books and adult fiction.

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missing link British  

noun

1. (sometimes capitals) a hypothetical extinct animal or animal group, formerly thought to be intermediate between the anthropoid apes and man

2. any missing section or part in an otherwise complete series

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missing link Cultural  

1. A supposed animal midway in evolution between apes and humans. The term is based on a misunderstanding about the theory of evolution, which does not state that humans are descended from apes, but rather maintains that both humans and apes descended from a common ancestor. Modern evolutionary scientists do not search for a “missing link.”

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Etymology

Origin of missing link

First recorded in 1850–55

Example Sentences

The Zambian segment of the Lobito Corridor -- often described as the missing link -- is not on LAR's near-term agenda, he added, citing the scale and cost of rehabilitating the rail infrastructure.

From Barron's • May 7, 2026

Dulles came to believe that religion, specifically an ecumenical Protestantism aiming to promote cooperation among different sects, was the missing link that could provide a moral architecture for the global system.

From The Wall Street Journal • Apr. 15, 2026

"This was the missing link that explains how a normal immune response can, in very rare cases, become harmful."

From Science Daily • Apr. 10, 2026

“It’s kind of a missing link in the system, through a fairly densely populated part of the city,” Elkind said of the proposed K Line extension.

From Los Angeles Times • Mar. 24, 2026

The missing link, in all cases, was information.

From "The Gene" by Siddhartha Mukherjee