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

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

And first-time buyers, long a missing link of the housing market, represented some 34% of February sales, one of the highest rates in five years, according to National Association of Realtors data.

From Barron's • Mar. 14, 2026

That thought gives me the missing link in the chain of thought I was trying to find.

From "Insurgent" by Veronica Roth