Knaik, a rivulet of Ardoch parish, Perthshire, rising at a spot 4¼ miles S by W of Comrie and 1470 feet above sea-level, and running 9³/8 miles south-eastward past Braco Castle, the Roman camp of Ardoch, and Braco village, till, after a total descent of 1000 feet, it falls into Allan Water in the vicinity of Greenloaning railway station.—Ord. Sur., sh. 39, 1869.

(F.H. Groome, Ordnance Gazetteer of Scotland (1882-4); © 2004 Gazetteer for Scotland)