pileus

/ˈpɪliəs/

//ˈpɪliəs// noun

"pileus" is a 6-letter English headword indexed on PlainSpell.

The verdict

“pileus” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
6
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The cap of a mushroom.

Corpus desk

Index EN-pileus · pileus · English

pileus · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-LONG 6 letters
  • VOW-3 3 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "P" thin
  • PHOTO-UNK Peer pending

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Key facts for pileus
PropertyValue
Headwordpileus
LanguageEnglish
Part of speechNoun
IPA/ˈpɪliəs/
Letters6
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “pileus” in English

pileusfalls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

pileus is uncommon English outside the top frequency list, classed as anoun, transcribed /ˈpɪliəs/. Rarity is why readers land here mid-draft. 5 senses are on record.

pileus has no tracked misspelling variants, suggesting the orthography follows predictable English patterns. This entry stands alone in our confusable dataset, since no other headword is close enough in sound or shape to pair with it.

Etymologically, the entry records: Borrowed from Latin pīleus, a form of pilleus (“a felt cap”). The correct English form is pileus, spelled P-I-L-E-U-S.

Definition

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

Recorded use

Wiktionary examples

These source excerpts show how pileus appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. The stem is easily separable from the pileus at its junction, in this respect being similar to Amanita, Amanitopsis, Lepiota and others.
  2. One must check the size and shape of the pileus as well as its color. Many weird and unexpected shapes are found in the mushroom kingdom.

Etymology

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

This word in other languages

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "pileus"?
"pileus" is spelled P-I-L-E-U-S. The IPA pronunciation is /ˈpɪliəs/.
What does "pileus" mean?
As a noun, "pileus" means: The cap of a mushroom.
How do you pronounce "pileus"?
The IPA (International Phonetic Alphabet) transcription for "pileus" is /ˈpɪliəs/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "pileus"?
Borrowed from Latin pīleus, a form of pilleus (“a felt cap”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list