plan•e•tes•i•malPronunciation: (plan"i-tes'u-mul), [key] Astron.
one of the small celestial bodies that, according to one theory (planetes'imal hypoth'esis),
were fused together to form the planets of the solar system.
of or pertaining to a planetesimal or planetesimals.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.