To harbor means to provide shelter or refuge to someone or something. It involves offering a place of protection and safety, typically by allowing them to stay or remain in a particular location. This can refer to physical locations such as buildings, shelters, or even personal homes where individuals or animals are given a temporary or permanent residence.

In a figurative sense, to harbor can also describe the act of keeping or nurturing certain thoughts, feelings, or emotions within oneself. It involves retaining and maintaining these thoughts or emotions, possibly without expressing or acting upon them. This can range from harboring negative or harmful thoughts to harboring positive or nurturing emotions.

Additionally, to harbor can also describe the act of secretly or illegally hiding someone or something, especially when it is against the law or societal norms. It is often associated with concealing individuals who are being pursued by authorities or hiding illegal goods. Harboring in this sense implies a level of secrecy and complicity.

Overall, to harbor implies the act of providing shelter, protection, or refuge either physically or emotionally. It can refer to harboring someone or something within a physical location, concealing thoughts and emotions within oneself, or hiding someone or something illicitly.