From Conservapedia - Reading time: 2 minA sacred cow is an idea, object, person, or other thing considered so sacred or valuable to a person or group that it is considered immune from criticism, or (more commonly) criticism is considered morally reprehensible in and of itself.
Sacred cows can be identified by the disproportionate personal attacks and/or censorship elicited by criticism.
Examples of contemporary sacred cows (which are, as a whole, also defended collectively by the Left) include:
The term comes from belief in Hindu (and other ancient religions) that cows are holy, and must therefore not be eaten or otherwise harmed. In Hinduism, cows are believed to be reincarnated humans; therefore, Hindus do not eat beef or kill cows and they are left to wander aimlessly through city streets and across busy roads. Similarly, many other ancient religions (such as Zoroastrianism) worshipped cows, and the Israelites created a Golden calf to worship in the wilderness in the time of Moses after he led them out of slavery in Egypt.
The use of the term as a simile and metaphor originated in the United States in the late 19th century. For example: