high-vocab
Words that are rarely used and unknown to most people. Often words that only relate to very specific circumstances or topics. For example, tyromancy, (the long ago debunked method of divination by reading cheese molds) is a word that very few people know or use. It also relates to an activity that is no longer practiced.
She was known for getting excited about high-vocab, frequently using words none of us had ever encountered, even when we were all studying for the SATs.