1. Not changing or varying; continuous: a constant gentle rain; drove at a constant speed.
2. Happening regularly or repeatedly; continual: the constant barking of the dog next door; constant interruptions. See Synonyms at continual.
3. Unchanging in nature, value, or extent; invariable: a constant wind speed.
4. Steadfast in purpose, loyalty, or affection; faithful: a constant friend. See Synonyms at faithful.
1. Something that is unchanging or invariable.
a. A quantity assumed to have a fixed value in a specified mathematical context.
b. An experimental or theoretical condition, factor, or quantity that does not vary or that is regarded as invariant in specified circumstances.
[Middle English, from Old French, from Latin cōnstāns, cōnstant-, present participle of cōnstāre, to stand firm : com-, intensive pref.; see COM- + stāre, to stand; see stā- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.