Pileus
//ˈpɪliəs// noun
noun ·Uncommon ·Advanced level
Definitions
Noun
- 1 The cap of a mushroom.
"The stem is easily separable from the pileus at its junction, in this respect being similar to Amanita, Amanitopsis, Lepiota and others."
- 2 a fruiting structure resembling an umbrella or a cone that forms the top of a stalked fleshy fungus such as a mushroom wordnet
- 3 The bell of a jellyfish.
- 4 A small thin cloud attached to a cumulus cloud.
"The most short-lived of all the accessory clouds, pileus is also the most beautiful."
- 5 A conical felt hat worn in Ancient Rome and Greece. Ancient-Rome, historical
"Among the Romans the cap of felt was the emblem of liberty. When a slave obtained his freedom he had his head shaved, and wore instead of his hair an undyed pileus."
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- 6 The top of the head of a bird, from the bill to the nape.
Example
More examples"The stem is easily separable from the pileus at its junction, in this respect being similar to Amanita, Amanitopsis, Lepiota and others."
Etymology
Borrowed from Latin pīleus, a form of pilleus (“a felt cap”).
Related phrases
More for "pileus"
Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.