Definition from Nolo’s Plain-English Law Dictionary
Information exchanged between two people who (1) have a relationship in which private communications are protected by law, and (2) intend that the information be kept in confidence. The law recognizes certain parties whose communications will be considered confidential and protected, including spouses, doctor and patient, attorney and client, and priest and confessor. Communications between these individuals cannot be disclosed in court unless the protected party waives that protection. The intention that the communication be confidential is critical. For example, if an attorney and his client are discussing a matter in the presence of an unnecessary third party -- for example, in an elevator with other people present -- the discussion will not be considered confidential and may be admitted at trial. Also known as privileged communication.