Swore is the past tense of swear, which has several meanings:

1. To make a serious, formal promise. When someone is sworn in as president or takes the witness stand in court, they swear to tell the truth or faithfully perform their duties. Knights in medieval times swore loyalty to their king. When you swear to keep a secret, you're making a binding promise you intend to keep.
2. To use offensive or vulgar language, also called cursing or using profanity. If someone swore after stubbing their toe, they used words considered inappropriate or disrespectful. Different families and settings have different standards for what counts as swearing. Words acceptable at home might not be appropriate at school or in formal situations.