"rock or metallic mass floating in space," which becomes a meteor when it enters Earth's atmosphere and a meteorite when it strikes, 1865, formed in English from meteor + -oid.
Entries linking to meteoroid
meteor n.
late 15c., "any atmospheric phenomenon," from Old French meteore (13c.) and directly from Medieval Latin meteorum (nominative meteora), from Greek ta meteōra "the celestial phenomena, things in heaven above," plural of meteōron, literally "thing high up," noun use of neuter of meteōros (adj.) "high up, raised from the ground, hanging," from meta "by means of" (see meta-) + -aoros "lifted, lifted up, suspended, hovering in air," related to aeirein "to raise" (from PIE root *wer- (1) "to raise, lift, hold suspended").
Specific sense of "fireball in the sky, shooting star" is attested from 1590s. Atmospheric phenomena were formerly classified as aerial meteors (wind), aqueous meteors (rain, snow, hail), luminous meteors (aurora, rainbows), and igneous meteors (lightning, shooting stars). All the other senses have fallen away. When still in space beyond the atmosphere it is a meteoroid; when fallen to earth it is a meteorite. A periodically recurring fall of them (usually associated with a comet) is a meteor shower (by 1853).
-oid
word-forming element meaning "like, like that of, thing like a ______," from Latinized form of Greek -oeidēs (three syllables), from eidos "form," related to idein "to see," eidenai "to know;" literally "to see" (from PIE *weid-es-, from root *weid- "to see"). The -o- is connective or a stem vowel from the previous element. Often implying an incomplete or imperfect resemblance to the thing indicated.