What is a Sacred Cow?
A sacred cow is something which is immune to criticism by virtue of its high status. This term is often used in a sardonic way, to describe something which is excessively venerated to the point that people are afraid to criticize it. When discussing a sacred cow, the implication is that it must be handled very carefully to avoid causing offense. This slang term is used in many English-speaking countries, although some people find it offensive because of its origins.