• WordNet 3.6
    • n planetoid any of numerous small celestial bodies that move around the sun
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Webster's Revised Unabridged Dictionary
    • n Planetoid (Astron) A body resembling a planet; an asteroid.
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Century Dictionary and Cyclopedia
    • n planetoid One of the group of very small planets revolving round the sun between the orbits of Mars and Jupiter, remarkable for the eccentricity of their orbits and the greatness of their angle of inclination to the ecliptic; a minor planet; an asteroid. The diameter of the largest is supposed not to exceed 450 miles, while most of the others are believed to be very much smaller. Ceres was the first to be detected, being observed for the first time by Piazzi, an Italian astronomer, on January' 1st, 1801; since 1847 no year has passed without the discovery of new planetoids. The number now known exceeds 290; 10 were discovered in 1888, 6 in 1889, and 5 in the first four months of 1890.
    • n planetoid See minor planet.
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Chambers's Twentieth Century Dictionary
    • n Planetoid a celestial body having the form or nature of a planet: one of a number of very small planets, often called asteroids, moving round the sun between Mars and Jupiter
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Webster's Revised Unabridged Dictionary
Planet, + -oid,
Chambers's Twentieth Century Dictionary
Fr. planète—Gr. planētēs, wanderer—planān, to make to wander.


In literature:

OLBERS, HEINRICH, German astronomer, born near Bremen; discovered five of the comets and the two planetoids Pallas and Vesta (1758-1840).
"The Nuttall Encyclopaedia" by Edited by Rev. James Wood
They are divided by the planetoids into an inner and an outer band.
"A Trip to Venus" by John Munro
I would suggest you observe the planetoid yourself with the magnascope and draw your own conclusions.
"Danger in Deep Space" by Carey Rockwell
To them life on a planet like Earth was as life to a terrestrian on a planetoid such as Ceres, Juno or Eros would have seemed.
"Invaders from the Infinite" by John Wood Campbell
We now know that it contains about nine hundred "planetoids," or small globes of from five to five hundred miles in diameter.
"The Outline of Science, Vol. 1 (of 4)" by J. Arthur Thomson
That conflict ended, he watched the Triplanetary fleet reform its battle cone and rush upon the planetoid.
"Triplanetary" by Edward Elmer Smith
But a planetoid is in a different class altogether.
"A Spaceship Named McGuire" by Gordon Randall Garrett
Between the orbits of Mars and Jupiter there revolves a remarkable group of small planets or planetoids.
"The Astronomy of Milton's 'Paradise Lost'" by Thomas Orchard
One of those little planetoids.
"The Copper-Clad World" by Harl Vincent
Already, Z-40 has cost us more than we could clear from the sale of half a dozen planetoids.
"The Planetoid of Peril" by Paul Ernst

In news:

Thursday and Friday offer the best chance to track down the only planet never visible to the unaided eye: Neptune, the most distant planet in the solar system since Pluto's demotion to planetoid status several years ago.
Aslan King, The Evil Streaks, Planetoid .
The New Planetoid Beyond Pluto.

In science:

On 14 or 15 October 1874 [4 or 5 Ramadan 1291H], an occurrence of planetoids with great and troubling chaos where some of them were coming from the east, others coming from the west while others from other directions.
New additional material of meteor showers during 9th -19th centuries in the Islamic history