pileus

American  

[pahy-lee-uhs, pil-ee-] / ˈpaɪ li əs, ˈpɪl i- /

noun

• pilei,
  plural
• pileus
  plural

1. Mycology. the horizontal portion of a mushroom, bearing gills, tubes, etc., on its underside; a cap.

2. Zoology.

   1. the umbrella or bell of a jellyfish.

   2. pileum.

3. Also called cap cloud, scarf cloud. Meteorology. a small, thin cloud just above or attached to a growing cumulus cloud.

4. a felt skullcap worn by the ancient Romans and Greeks.

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pileus British  

/ ˈpaɪlɪəs, ˈpɪl- /

noun

1. the upper cap-shaped part of a mushroom or similar spore-producing body

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pileus Scientific  

/ pī′lē-əs /

• pilei
  plural

1. 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.

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Other Word Forms

Noun Inflected Forms

• pilei
  plural
• pileus
  plural

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Etymology

Origin of pileus

1750–60; < New Latin, special use of Latin pīleus skullcap; akin to Greek pîlos felt, felt cap

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Example Sentences

See Examples For:

pileus pilei

This species is unique for the dorsal attachment of its stipe to the top of the pileus, and the abundant cystidia covering all surfaces of the fruiting body.

From Salon ● Apr. 26, 2025

The reverse features two daggers on either side of a cap known as a pileus.

From New York Times ● Mar. 22, 2023

A cumulus, for example, might just be a cumulus; or it might be a cumulus fractus, if its edges are tattered; or a cumulus pileus, if a smaller cloud appears over it like a hood.

From New York Times ● May 4, 2016

L. sistrata differs in fibrillose stem and pileus covered with glistening particles.

From European Fungus Flora: Agaricaceae by George Massee

P. 1-1.5 cm. resupinate, then reflexed, tomentose, white, attached by a very short incurved downy stem which disappears when the pileus turns over; g. radiating from an excentric point, distant, white then pink; sp.

From European Fungus Flora: Agaricaceae by George Massee

P. up to 1 cm. convex, papillate, grey, subtomentose; g. adnate; s. 3-5 cm. base dark, springing from a blackish sclerotium; several minute stems with abortive pilei often spring from the stem; sp.

From European Fungus Flora: Agaricaceae by George Massee

The general character is shown in the illustration, being nearly white but many of the pilei are somewhat smoky.

From The Mushroom, Edible and Otherwise Its Habitat and its Time of Growth by Miron Elisha Hard

The pilei are imbricated, fibrous, scaly, margin fimbriated, at first dirty white.

From The Mushroom, Edible and Otherwise Its Habitat and its Time of Growth by Miron Elisha Hard

The pilei are pulvinate, narrow, zoned, often laterally confluent; ochraceous-white, tomentose, then smooth, laccate.

From The Mushroom, Edible and Otherwise Its Habitat and its Time of Growth by Miron Elisha Hard

Fasciculate, 2-3 pilei often appearing to spring from a branched stem. umbonatus, Fr.

From European Fungus Flora: Agaricaceae by George Massee

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