Bullshit (also bullshite or bullcrap) is a common English expletive which may be shortened to the euphemism bull or the initialism B.S. In British English, "bollocks" is a comparable expletive. It is mostly a slang term and a profanity which means "nonsense", especially as a rebuke in response to communication or actions viewed as deceptive, misleading, disingenuous, unfair or false. As with many expletives, the term can be used as an interjection, or as many other parts of speech, and can carry a wide variety of meanings. A person who excels at communicating nonsense on a given subject is sometimes referred to as a "bullshit artist" instead of a "liar."

In philosophy and psychology of cognition the term "bullshit" is sometimes used to specifically refer to statements produced without particular concern of truth, to distinguish from a deliberate, manipulative lie intended to subvert the truth. In business and management, guidance for comprehending, recognizing, acting on and preventing bullshit, are proposed for stifling the production and spread of this form of misrepresentation in the workplace, media and society. Within organizations bullshitting is considered to be a social practice that people engage with to become part of a speech community, to get things done in that community, and to reinforce their identity. Research has also produced the Organizational Bullshit Perception Scale (OBPS) that reveals three factors of organizational bullshit (regard for truth, the boss, and bullshit language) that can be used to gauge perceptions of the extent of organizational bullshit that exists in a workplace.

The word is generally used in a depreciatory sense, but it may imply a measure of respect for language skills or frivolity, among various other benign usages. In philosophy, Harry Frankfurt, among others, analyzed the concept of bullshit as related to, but distinct from, lying; the liar tells untruth, the bullshitter aims to convey a certain impression of themselves without being concerned about whether anything at all is true—it may be.

As an exclamation, "Bullshit!" conveys a measure of dissatisfaction with something or someone, but this usage need not be a comment on the truth of the matter.