The producer of an effect, result, or consequence. The one, such as a person, event, or condition, that is responsible for an action or result. A basis for an action or response; a reason: The doctor's report gave no cause for alarm. A goal or principle served with dedication and zeal: "the cause of freedom versus tyranny\u201d ( Hannah Arendt). The interests of a person or group engaged in a struggle: "The cause of America is in great measure the cause of all mankind\u201d ( Thomas Paine). Law A ground for legal action. Law A lawsuit. A subject under debate or discussion. To be the cause of or reason for; result in. To bring about or compel by authority or force: The moderator invoked a rule causing the debate to be ended.