Asserting that something is true or correct, as with the answer "yes": an affirmative reply. Giving assent or approval; confirming: an affirmative vote. Positive; optimistic: an affirmative outlook. Logic Of, relating to, or being a proposition in which the predicate affirms something about the subject, such as the statement apples have seeds. A word or statement of agreement or assent, such as the word yes. The side in a debate that upholds the proposition: Her team will speak for the affirmative.