A strath is a large valley, typically a river valley that is wide and shallow (as opposed to a glen which is typically narrower and deep).
An anglicisation of the Gaelic word srath, it is one of many that have been absorbed into common use in the English language. It is commonly used in rural Scotland to describe a wide valley, even by non-Gaelic speakers.
It occurs in numerous Scottish place names (such as Strathspey and Strathclyde), Strath-Taieri in New Zealand, Strathfield, a suburb of Sydney, Australia, Strathewen, Victoria, Australia, Strathmore, Alberta and various places in Canada named Strathcona.
It also occurs in the names of five Peninsular and Oriental Steam Navigation Company liners, four of which, the Strathhaird, the Strathnaver, the Stratheden and the Strathmore brought thousands of migrants to Australia between the 1950s and the 1960s. The ships acted as troop carriers during the Second World War and the fifth ship, the Strathallan, sank in the Mediterranean in 1942 taking troops to the landings in North Africa.
The word is related to Old Welsh Ystrad, as in Ystrad Clud, the Old Welsh name for the Kingdom of Strathclyde.
In Keith there is a distillery producing the Strathisla whisky. It is a single malt whisky that is also an ingredient to the blend Chivas Regal.