a. Emitting light, especially in the dark; shining.
b. Reflecting light; illuminated: "He watched a luminous cloud drifting up from the Gulf" (Tim Gautreaux). See Synonyms at bright.
2. Having a high degree of saturation: a luminous green.
a. Presented or perceived clearly or vividly: luminous memories.
b. Enlightened or intelligent: luminous ideas.
[Middle English, from Old French lumineux, from Latin lūminōsus, from lūmen, lūmin-, light; see leuk- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.