'Strath' definitions:

Definition of 'Strath'

From: GCIDE

Strath \Strath\, n. [Gael. srath.] A valley of considerable size, through which a river runs; a valley bottom; -- often used in composition with the name of the river; as, Strath Spey, Strathdon, Strathmore. [Scot.] [1913 Webster]
The long green strath of Napa valley. --R. L. Stevenson. [1913 Webster]