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.
noun plural -lei (-lɪˌaɪ)
- the upper cap-shaped part of a mushroom or similar spore-producing body
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.