red dwarfn. A dwarf star, ranging in mass from one-tenth to one-half the mass of the sun, whose relatively cool surface temperature makes it appear red-orange in color.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.red dwarf n (Celestial Objects) one of a class of small cool main-sequence stars Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014red? dwarf? n. any of the faint reddish stars smaller than the sun and with low surface temperatures, about 2000?3000 K. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.red dwarf A star that is cool, small, and very faint. Red dwarfs burn very slowly and live for about 100 billion years. Although they are difficult to see, they are likely the most abundant type of star. Proxima Centauri is a red dwarf.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.