n. A relatively small (sand- to boulder-sized) fragment of debris in a solar system that produces a meteor when it hits the atmosphere
the GNU version of the Collaborative International Dictionary of English
n. A small body moving through space, or revolving about the sun, which on entering the earth's atmosphere would be deflagrated and appear as a meteor.
The Century Dictionary and Cyclopedia
n. A body traveling in space, and of the same nature as those which on entering the earth's atmosphere become visible as meteors.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. (astronomy) any of the small solid extraterrestrial bodies that hits the earth's atmosphere
Word Usage
"A meteoroid is matter revolving around the sun or any object in interplanetary space that is too small to be called an asteroid or a comet."