# pileus

> English word · Noun · IPA /ˈpɪliəs/

## Definitions
1. The cap of a mushroom.
2. The bell of a jellyfish.
3. A small thin cloud attached to a cumulus cloud.
4. A conical felt hat worn in Ancient Rome and Greece.
5. The top of the head of a bird, from the bill to the nape.

## Etymology
Borrowed from Latin pīleus, a form of pilleus (“a felt cap”).

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/pileus