Allegheny \Al"le*ghe`ny\, a.

1. Of or pertaining to the Allegheny Mountains, or the region where they are situated. Also

Source: Webster's Revised Unabridged Dictionary (1913)
 

Appalachian \Ap`pa*la"chi*an\, a. Of or pertaining to a chain of mountains in the United States, commonly called the Allegheny mountains.

Note: The name Appalachian was given to the mountains by the Spaniards under De Soto, who derived it from the neighboring Indians. --Am. Cyc.

Source: Webster's Revised Unabridged Dictionary (1913)