<p><strong>Adjective</strong></p><ul><li>without formality or ceremony; casual: an informal visit.</li><li>not according to the prescribed, official, or customary way or manner; irregular; unofficial: informal proceedings.</li><li>suitable to or characteristic of casual and familiar, but educated, speech or writing.</li><li>Grammar: characterizing the second singular pronominal or verbal form, or its use, in certain languages: the informal "tu" in French.</li></ul><p><strong>Synonyms</strong></p><ul><li>easy, natural</li></ul><p><strong>Synonyms</strong></p><ul><li>unconventional</li></ul><p><strong>Antonyms</strong></p><ul><li>conventional</li></ul>