A male given name from the Celtic languages, a less common spelling of Alan. / A surname transferred from the given name derived from the given name, more often spelled Allen.

A hill range in the Transantarctic Mountains, Antarctica

A small town in Stirling council area, Scotland, situated on the river Allan Water (OS grid ref NS7997).

A river in Stirling council area, Scotland, which joins the River Forth. / A stream in the Scottish Borders council area, Scotland, which joins the River Teviot at Newmill.

A rare brain-development disorder, almost exclusively in males, that causes moderate to severe mental retardation and problems with movement.

A surname.