sub·​stel·​lar | \ ˌsəb-ˈste-lər How to pronounce substellar (audio) \
variants: or sub-stellar

Definition of substellar

of a celestial object
: having less mass than a star : not having the mass required to sustain nuclear fission Subsequent hunts within young stellar clusters have flushed out droves of brown dwarfs. Prime targets are the Pleiades cluster and star-forming regions in Orion and Taurus, where substellar bodies rival stars in number.— Robert Irion Very often, the most publicized events in astronomy involve the detection of fundamentally new types of objects. The discovery of a substellar object, a "brown dwarf" some dozens of times as massive as Jupiter, falls in this category.Physics Today

First Known Use of substellar

1949, in the meaning defined above

Keep scrolling for more

Learn More about substellar

Time Traveler for substellar

Time Traveler

The first known use of substellar was in 1949

See more words from the same year

Statistics for substellar

Cite this Entry

“Substellar.” Dictionary, Merriam-Webster, Accessed 1 Dec. 2020.

Comments on substellar

What made you want to look up substellar? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Musical Words Quiz

  • gramophone
  • Which word describes a musical performance marked by the absence of instrumental accompaniment?
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!