لمكان الاشتباه بها لفظاً أو معنى
Because they resemble those premises in wording or in meaning.
In verbal ambiguity, a word appears unchanged while its intended sense shifts. Arabic ʿayn can mean an eye or a spring. “Every ʿayn sees; this spring is an ʿayn; therefore this spring sees” trades on two meanings of one expression.
The key point is that identity of words is not identity of meanings. A shifting middle term can make invalid reasoning look orderly, even when the language resembles a syllogism.