Mary LeCron Foster (February 1, 1914 – December 9, 2001) was an American anthropological linguist, who spent most of her working life at the Department of Anthropology at the University of California, Berkeley. Foster carried out graduate work in anthropology under the direction of Ruth Benedict. The influence of Franz Boas, whom she also knew at Columbia, may be seen in Foster’s interests in symbolism and language origins. In addition to writing grammars of Sierra Popoluca and Purépecha, she published several articles purporting to reconstruct spoken Primordial Language (PL). PL, she maintained, was constructed out of speech sounds she dubbed ‘phememes’ that were at the same time roots, whose meaning was motivated by the shaping and movement of the vocal tract.