swears

The word "swear" can be used as a noun or a verb. As a noun, it refers to a curse word or an oath. As a verb it can mean to take an oath, make a lasting promise, or to use a curse word, etc. In this stanza the verb definition is used when the speaker's lover "swears" that she does not lie to him and that she is being faithful. Because the word "swear" also refers to the use of curse words that are profane due to vulgar use, it may have also been used by the author to make a reference to the profane and vulgar things that the mistress is secretly doing.
 * Swears**