In term logic, a "proposition" is simply a "form of language": a particular kind of sentence, in which the subject and predicate are combined, so as to assert something true or false. It is not a thought, or an abstract entity. The word ""propositio"" is from the Latin, meaning the first premise of a syllogism. Aristotle uses the word premise ("protasis") as a sentence affirming or denying one thing or another ("Posterior Analytics" 1. 1 24a 16), so a premise is also a form of words.