Wiktionary
mithridatism
n. The development of immunity to a poison by gradual ingestion of successively greater amounts.
Wikipedia
Mithridatism
Mithridatism is the practice of protecting oneself against a poison by gradually self-administering non-lethal amounts. The word is derived from Mithridates VI, the King of Pontus, who so feared being poisoned that he regularly ingested small doses, aiming to develop immunity.
Usage examples of "mithridatism".
He was called back to the Seminary for a refresher course, and it was at that time that he developed a taste for schnapps, and started the course of mithridatism which was to serve him so well in his later years.