The largest terrier breed is the AIREDALE, which has 8 letters. The AIREDALE is a breed of working terrier originating from the Aire Valley in Yorkshire, England. It is sometimes called the 'King of Terriers' due to its size and stature. The AIREDALE is a strong, courageous and loyal breed that is known for its intelligence and trainability. It is an active and energetic breed that makes an excellent companion and guard dog.