acyl

/ˈæ.sɪl/

//ˈæ.sɪl// noun

"acyl" is a 4-letter English headword indexed on PlainSpell.

The verdict

“acyl” is uncommon English (frequency #53,983 among 3,931 “A” headwords), classed as a noun. The kind of spelling people second-guess.

#53,983
frequency rank, English
3,931
“A” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Any of class of organic radicals, RCO-, formed by the removal of a hydroxyl group from a carboxylic acid.

Corpus desk

Index EN-acyl · acyl · English

acyl · rank #53,983 · 0 variants · 0 confusables

  • FREQ-RARE #53,983
  • LEN-MID 4 letters
  • VOW-2 2 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 3,931
  • PHOTO-FINISH acquiesce

Nearest frequency peer: acquiesce (-1 rank slots)

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.

Long-tail ranks near “acyl”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “acyl” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for acyl
PropertyValue
Headwordacyl
LanguageEnglish
Part of speechNoun
IPA/ˈæ.sɪl/
Letters4
Frequency rank#53,983
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “acyl” in English

Word frequency stretches from the small set of words we reach for constantly (left) out to the long tail barely used once in a while (right).acylfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Rare peers in the same band: “acquiesce” (#53,982), “Adcock” (#53,984), “acker” (#53,981). Among 3,931 “A” headwords, “acyl” is #53,983. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

acyl is uncommon English at frequency #53,983 among 3,931 “A” headwords, classed as anoun, transcribed /ˈæ.sɪl/. Rarity is why readers land here mid-draft. Gloss: "Any of class of organic radicals, RCO-, formed by the removal of a hydroxyl group from a carboxylic acid.".

acyl doesn't appear in our generated misspelling index, typically a sign the spelling maps closely to how the word sounds. We don't track a confusable pairing for this entry, a sign it's visually distinctive enough not to be mixed up with another word.

Etymologically, the entry records: Ultimately from Latin ac(eō) + -yl. The correct English form is acyl, spelled A-C-Y-L.

Definition

  1. 1
    Any of class of organic radicals, RCO-, formed by the removal of a hydroxyl group from a carboxylic acid.

Recorded use

Wiktionary example

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

  1. From ethyleneoxides or ethyleneimines carrying an acyl substituent, with hydrazine and its derivatives (Ch. 3. XV).

Etymology

Ultimately from Latin ac(eō) + -yl.

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); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "acyl"?
"acyl" is spelled A-C-Y-L. The IPA pronunciation is /ˈæ.sɪl/.
What does "acyl" mean?
As a noun, "acyl" means: Any of class of organic radicals, RCO-, formed by the removal of a hydroxyl group from a carboxylic acid.
How do you pronounce "acyl"?
The IPA (International Phonetic Alphabet) transcription for "acyl" is /ˈæ.sɪl/. 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 "acyl"?
Ultimately from Latin ac(eō) + -yl. 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.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "acyl", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 4 letters (nearest by frequency rank).

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

Source: FrequencyWords open word-frequency list