Entry 1 sense Webster, 1913 Assertive /əs-ẽrt'-ĭv/ · As·sert·ive · IPA /əˈsɝtɪv/ 01 a. Positive; affirming confidently; affirmative; peremptory. 1. Positive; affirming confidently; affirmative; peremptory. “In a confident and assertive form.” — Glanvill.