- 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.
- 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.
- a hypothetical extinct animal or animal group, formerly thought to be intermediate between the anthropoid apes and man
- any missing section or part in an otherwise complete series
