Senecas \Sen"e*cas\, n. pl.; sing. {Seneca}. (Ethnol.)
A tribe of Indians who formerly inhabited a part of Western
New York. This tribe was the most numerous and most warlike
of the Five Nations.

{Seneca grass}(Bot.), holy grass. See under {Holy}.

{Seneca eil}, petroleum or naphtha.

{Seneca root}, or {Seneca snakeroot} (Bot.), the rootstock of
an American species of milkworth ({Polygala Senega})
having an aromatic but bitter taste. It is often used
medicinally as an expectorant and diuretic, and, in large
doses, as an emetic and cathartic. [Written also {Senega
root}, and {Seneka root}.]