1. Lacking or exhibiting a lack of good sense or judgment; silly: a foolish boy; a foolish purchase.
2. Capable of arousing laughter; absurd or ridiculous: a foolish grin.
3. Embarrassed; abashed: I feel foolish telling you this.
4. Insignificant; trivial: foolish little knickknacks.
Synonyms: foolish, absurd, fatuous, ludicrous, preposterous, ridiculous, silly
These adjectives are applied to people or things that show an absence of good judgment or common sense: a foolish expenditure of energy; an absurd idea that is bound to fail; fatuous optimism that does not take the real problem into account; dismissed her ludicrous criticism; a preposterous excuse that no one believed; offered a ridiculous explanation for his tardiness; a silly argument.
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.