Legal maxim and Latin for A hidden ambiguity of the words may be interpreted by evidence; for an ambiguity which arises from an extrinsic fact may be removed by proof of such fact. If words in a document are unclear, evidence to explain the meaning or interpretation or intent may be heard. If the evidence is useful, then the ambguity and lack of clarity of the meaning of those words is removed by good evidence which explains and brings clear meaning to the words.