blanz (abha`bu`ah: only in Ex 9:9,10): Pustules containing fluid around a boil or inflamed sore. It is an Old English word "bleyen," used sometimes as a synonym for boil. Wyclif (1382) uses the expression "stinkende bleyne" for Job's sores. The Hebrew word is from a root which means that which bubbles up.
See BOIL.