planetesimal

 
Pronunciation: /ˌplanɪˈtɛsɪm(ə)l/
Astronomy

noun

  • a minute planet; a body which could come together with many others under gravitation to form a planet.

adjective

  • denoting or relating to planetesimals: the planetesimal material orbiting the sun

Origin:

early 20th century: from planet, on the pattern of infinitesimal