Diehard Sort is a term used to describe someone who is extremely passionate and dedicated to a cause or belief. It is often used to describe someone who is willing to go to great lengths to defend their beliefs, even in the face of adversity. The term is derived from the word 'ZEALOT, ' which means someone who is fanatically devoted to a cause or ideal. This term is often used to describe someone who is willing to fight for what they believe in, no matter the cost.