<p><strong>Noun</strong></p><ul><li>a person or thing that explores.</li><li>a person who investigates unknown regions: the great explorers of the Renaissance.</li><li>any instrument used in exploring or sounding a wound, a cavity in a tooth, or the like.</li><li>Also called Explorer Scout: a person between the ages 14 and 20 who is an active participant in the exploring program sponsored by the Boy Scouts of America.</li><li>Aerospace: one of a long series of U.S. scientific satellites: Explorer 1 (1958) was the first U.S. artificial satellite.</li></ul>