Definition of allegheny:
(n) :
(with "the") The Allegheny River in Pennsylvania.
(n) :
Allegheny Mountain (Pennsylvania), a major mountain ridge in the northern part of the Allegheny Mountains.
(n) :
Allegheny Mountain (West Virginia โ Virginia), a major mountain ridge in the southern part of the Allegheny Mountains.
(n) :
(dated, attributively) The Allegheny Mountains.
(n) :
(dated, attributively) Appalachia.
(n) :
Any of several towns or counties in Pennsylvania, Virginia, North Carolina and Kentucky.