the term is usde in Mishna Shabbos 14:4. the context is that if one feels pain in his teeth on Shabbos he can’t fill his mouth with vinegar, as long as he dosen’t spit it out, because if he spits, it is for medicinal purposes. But he CAN dip bread in vinegar, and if he is healed, he is healed, and he isn’t ????. the prohibition stated here only applies when it is a small pain, but when it is an a big pain, in the words of the Taz on Orach Chayim 328:32: A big pain throughout his body, it is permitted to rinse and spit with vinegar.
