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.

---

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

---

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.”

---

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

He's the missing link between Jeff Buckley and Harry Styles.

From BBC • Jan. 7, 2026

“The missing link at this point, from my perspective, is the partnership with the parents and the families,” board member Judy Manouchehri said.

From Los Angeles Times • Mar. 3, 2024

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

From "Insurgent" by Veronica Roth