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mush·room (mŭshrm, -rm)
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n.
1.
a. Any of various fungi that produce a fleshy fruiting body, especially one consisting of a stalk with an umbrella-shaped cap.
b. Any of such fungi that are edible, especially the widely cultivated species Agaricus bisporus, which includes the button, cremini, and portobello mushrooms.
c. The usually aboveground fruiting body of any of such fungi.
d. One of these fruiting bodies that produce hallucinations when ingested. Also called magic mushroom.
2. Something shaped like one of these fungi.
intr.v. mush·roomed, mush·room·ing, mush·rooms
1. To multiply, grow, or expand rapidly: The population mushroomed in the postwar decades.
2. To swell or spread out into a shape similar to a mushroom.
3. To collect wild mushrooms.
adj.
1. Relating to, consisting of, or containing mushrooms: mushroom sauce.
2. Resembling mushrooms in rapidity of growth or evanescence: mushroom towns.

[Alteration of Middle English musheron, from Anglo-Norman mosserun, mushroom, agaric, from Old French mosseron, both from Vulgar Latin *mussariō, *mussariōn- (exact preform uncertain), edible agaric, mushroom (compare Catalan moixernó, edible agaric, chanterelle, and Occitan mossairon, edible agaric) possibly of pre-Roman substrate origin.]

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:

    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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