To forswear something, in the sense you will most often be asked about, is to give it up and bind yourself — by a kind of oath — not to go back to it. A person may forswear drink, violence, or an old loyalty. It is stronger and more literary than quit or give up; it has the feel of a promise spoken before witnesses. People in speech more often say swear off. Though actually the oldest English meaning was darker: to swear falsely, to lie under oath. That is why the word is built from for- (away, wrongly) plus swear, and why the adjective forsworn can still mean “having broken an oath.” Both pictures live in the verb: “I forswear this habit” (I swear I will stop) and, in older pages, “he forswore himself” (he swore what was not true). Past tense forswore; past participle forsworn.

發誓戒除、誓不再做、棄絕（文雅；口語較常說戒掉、發誓不再。古義也有「發假誓」）