وذلك بأن يكون الألفاظ مختلفة في الدلالة، فيقع فيه الاشتباه فيما هو المراد
The expressions differ in signification, producing confusion about the intended meaning.
A term's possessing multiple senses is not itself an error. The error occurs when one sense is used in one premise and another in the next while the reasoner treats them as one middle term.
The Arabic word “ʿayn” may refer to an eye or a water spring. If these senses are exchanged during an inference, the apparent identity of the word conceals a difference of meaning.