Pilt ‧ down Man /ˌpɪltdaʊn ˈmæn/ BrE AmE noun [uncountable]
an early type of human being that was believed to have existed because of a set of bones that were found in Sussex, southern England, in 1912. In 1953, however, scientific tests proved that the bones were not very old and that one of them belonged to an ↑ ape . It was then realized that the bones had been put there as a trick.