noun, plural pi·le·i [pahy-lee-ahy, pil-ee-ahy] /ˈpaɪ liˌaɪ, ˈpɪl iˌaɪ/ for 1, 2, 4, pi·le·us for 3.
Mycology. the horizontal portion of a mushroom, bearing gills, tubes, etc., on its underside; a cap.
- the umbrella or bell of a jellyfish.
Also called cap cloud, scarf cloud. Meteorology. a small, thin cloud just above or attached to a growing cumulus cloud.
a felt skullcap worn by the ancient Romans and Greeks.
Origin of pileus
1750–60; < New Latin, special use of Latin pīleus skullcap; akin to Greek pîlos felt, felt cap
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
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Historical Examples of pileus
British Dictionary definitions for pileus
noun plural -lei (-lɪˌaɪ)
the upper cap-shaped part of a mushroom or similar spore-producing body
Word Origin for pileus
C18 (botanical use): New Latin, from Latin: felt cap
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Plural pilei (pī′lē-ī′)
The umbrellalike fruiting structure forming the top of a fleshy fungus. It is supported by the stipe. The cap of a mushroom is a pileus.
The American Heritage® Science Dictionary
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