The term "undercover" refers to something or someone that is concealed, hidden or disguised. It can be used in a variety of contexts such as in law enforcement where an officer may go undercover to investigate criminal activity, in journalism where reporters may use a pseudonym to protect their identity while reporting on sensitive topics, and even in everyday life when someone might wear a disguise or mask to blend into a crowd. Essentially, the term "undercover" refers to something that is kept secret or hidden from view.