<p><strong>Adverb</strong></p><ul><li>out of doors; in the open air: He's happiest when he's outdoors.</li></ul><p><strong>Noun</strong></p><ul><li>(used with a singular verb) the world outside of or away from houses; open air: Our whole family likes the outdoors.</li></ul><p><strong>Adjective</strong></p><ul><li>outdoor.</li></ul>