英语词源字典 - 在线词源网站

Elizabeth [Elizabeth 词源字典]: fem. proper name, Biblical name of the wife of Aaron, from Late Latin Elisabeth, from Greek Eleisabeth, Eleisabet, from Hebrew Elishebha "God is an oath," the second element said by Klein to be related to shivah (fem. sheva) "seven," and to nishba "he swore," originally "he bound himself by (the sacred number) seven." Has never ranked lower than 26th in popularity among the names given to baby girls in the U.S. in any year since 1880, the oldest for which a reliable list is available. The city in New Jersey is named for Lady Elizabeth Carteret (d.1697), wife of one of the first proprietors of the colony.[Elizabeth etymology, Elizabeth origin, 英语词源]
forswear (v.): Old English forswerian "swear falsely" (intransitive), also "abandon or renounce on oath" (transitive), from for- "completely" + swerian "to swear" (see swear (v.)). Related: Forswore; forsworn; forswearing.
forsworn (adj.): from Old English forsworen, "perjured," past participle of forswerian "to swear falsely" (see forswear).
swear (v.): Old English swerian "take an oath" (class VI strong verb; past tense swor, past participle sworen), from Proto-Germanic *swarjan-, (cognates: Old Saxon swerian, Old Frisian swera, Old Norse sverja, Danish sverge, Middle Dutch swaren, Old High German swerien, German schwören, Gothic swaren "to swear"), from PIE root *swer- (1) "to speak, talk, say" (cognates: Old Church Slavonic svara "quarrel," Oscan sverrunei "to the speaker").

Also related to the second element in answer. The secondary sense of "use bad language" (early 15c.) developed from the notion of "invoke sacred names." Swear off "desist as with a vow" is from 1898. Swear in "install in office by administration of an oath" is from 1700 in modern use, echoing Old English.