a. Serious and dignified: a solemn occasion. See Synonyms at serious.
b. Showing or behaving with dignified restraint or earnestness: "Spade's face was solemn except for wrinkles at the corners of his eyes" (Dashiell Hammett).
2. Performed with full ceremony: a solemn High Mass.
3. Made with deep sincerity or invoking the force of religion: a solemn vow.
4. Dark or undecorated: a solemn forest; a solemn hall.
[Middle English solemne, from Old French, from Latin sollemnis, established, customary; see sol- 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.
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.