pileus

[ pahy-lee-uhs, pil-ee- ]

noun

, plural pi·le·i [pahy, -lee-ahy, pil, -ee-ahy] pi·le·us

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, 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.

pileus

/ ˈpɪl-; ˈpaɪlɪəs /

noun

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

pileus

/ pī′lē-əs /

, Plural pilei pī′lē-ī′

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.

Word History and Origins

Origin of pileus¹

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

Word History and Origins

Origin of pileus¹

C18 (botanical use): New Latin, from Latin: felt cap

Example Sentences

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

From New York Times

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

A genus of fungi having the under side of the pileus or cap composed of a multitude of fine separate tubes.

From Project Gutenberg

Two youths on horseback, probably the Dioscuri, though the conical cap, pileus, by which they are distinguished is wanting.

From Project Gutenberg

C, Longitudinal section of mature plant. p, The pileus. g, The gills. a, The annulus, or remnant of velum partiale, v, Remains of volva or velum universale. s, The stalk.

From Project Gutenberg