What is the definition or description of: lactase allergy?

Lactase deficiency: If you have lactose intolerance, you GI tract cannot break down the lactose which then gets to the lower bowel and be fermented by the normal bacterial residents in the gut leading to gas , discomfort , and even diarrhea. This is not an allergy. Taking lactase with dairy may resolve it. I have not seen or read about a case of lactase allergy.