Ambiguitas patens is the Latin term used to refer to a patent ambiguity. A patent ambiguity is an uncertainty or ambiguity that is present on the face of a document or instrument.
Ambiguitas paten is different from ambiguitas lateens, a latent ambiguity. Ambiguitas latens is a hidden ambiguity and can be corrected by extrinsic evidence. On the other hand, ambiguitas patens is open and apparent and cannot be removed or corrected by extrinsic evidence.