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lu·na·tic

(lnə-tĭk)

1. A person who is affected by lunacy; a mentally deranged person.

2. A very foolish person.

adj.

1. Affected by lunacy; mentally deranged.

2. Of or for people who are mentally deranged.

3. Wildly or giddily foolish: a lunatic decision.

[Middle English lunatik, from Old French lunatique, from Latin lūnāticus, from lūna, moon (from the belief that madness was influenced by the phases of the moon); see leuk- in the Appendix of Indo-European roots.]

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:

Indo-European Roots

Semitic Roots

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.

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