privilege of witness 1. Rule that a witness is not bound to answer certain types of question in legal proceedings. Examples: incriminating questions; questions relating to matters, publication of which might injure the state; questions relating to communications between counsel, solicitor and client on professional matters. 2. A witness is privileged (so that no action can be brought for defamation) to the extent of what he says during examination. What he says before he enters or after he has left the witness box is not privileged .