The Aireale Terrier (often shortened to "Airedale") is a terrier dog breed originating from Airedale in Yorkshire, England. It is sometimes called the "King of Terriers" because it is the largest of the terrier breeds, 50 to 100 pounds (23-45 kg). The breed has also been called the Waterside Terrier, because it was bred originally to hunt otters in and around the valleys of the River Aire from whence it gets its name.