adj. sil·li·er, sil·li·est
1. Having or exhibiting a lack of good judgment or common sense; foolish. See Synonyms at foolish.
2. Lacking seriousness or responsibleness; frivolous: indulged in silly word play; silly pet names for each other.
3. Semiconscious; dazed: knocked silly by the impact.
[Middle English seli, silli, blessed, innocent, hapless, from Old English gesælig, blessed.]
silli·ly (sĭlə-lē) adv.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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.