AYR, a river in Ayrshire, which takes its rise in the high grounds dividing the shire on the E. from Lanarkshire, and pursuing a westerly course for 18 miles, falls into the sea at the town to which it gives name. The volume of its waters is not large, but it sometimes shifts its bed, and does considerable damage. It contains those whetstones called Water-of-Ayr stones, which are exported in considerable quantities.