perfidy

/ˈpɜː.fɪ.di/

//ˈpɜː.fɪ.di// noun

By · According to Wiktionary data (CC BY-SA) ·

"perfidy" is a 7-letter English headword indexed on PlainSpell.

The verdict

“perfidy” is uncommon English (frequency #92,993 among 4,417 “P” headwords), classed as a noun. The kind of spelling people second-guess.

#92,993
frequency rank, English
4,417
“P” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A state or act of violating faith or allegiance; violation of a promise or vow, or of trust.

Corpus desk

Index EN-perfidy · perfidy · English

perfidy · rank #92,993 · 0 variants · 0 confusables

  • FREQ-RARE #92,993
  • LEN-LONG 7 letters
  • VOW-3 3 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 4,417
  • PHOTO-FINISH perforate

Nearest frequency peer: perforate (+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 “perfidy”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

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

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for perfidy
PropertyValue
Headwordperfidy
LanguageEnglish
Part of speechNoun
IPA/ˈpɜː.fɪ.di/
Letters7
Frequency rank#92,993
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “perfidy” in English

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right).perfidyfalls in this rarity band:

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

Scale is logarithmic (each tick is 10× rarer). Rare peers in the same band: “perforate” (#92,994), “penknife” (#92,991), “penetrator” (#92,990). Among 4,417 “P” headwords, “perfidy” is #92,993. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

perfidy is uncommon English at frequency #92,993 among 4,417 “P” headwords, classed as anoun, transcribed /ˈpɜː.fɪ.di/. Rarity is why readers land here mid-draft. 3 senses are on record.

The misspelling generator found no plausible variants for perfidy, which points to an orthography that plays by predictable English rules. Our confusable-pair dataset has no match for it, since nothing in our dataset looks or sounds close enough to cause mix-ups.

Etymologically, the entry records: From Middle French perfidie, from Latin perfidia from perfidus (“faithless, treacherous, false”), from fides (“faith”); related to, for example, English fidelity. The correct English form is perfidy, spelled P-E-R-F-I-D-Y.

Definition

  1. 1
    A state or act of violating faith or allegiance; violation of a promise or vow, or of trust.
  2. 2
    An illegitimate act of deception, such as using symbols like the Red Cross or white flag in a false claim of surrender to gain proximity to an enemy for purposes of attack.
  3. 3
    A state or act of deceit.

Recorded use

Wiktionary examples

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

  1. Stratagems must be carefully distinguished strategy from perfidy, since the former are allowed, whereas the latter is prohibited.
  2. Abuse of a protective emblem amounts to perfidy and constitutes a war crime under the customary law of armed conflict.

Etymology

From Middle French perfidie, from Latin perfidia from perfidus (“faithless, treacherous, false”), from fides (“faith”); related to, for example, English fidelity.

This word in other languages

perfidia(Español)perfidie(Français)

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 "perfidy"?
"perfidy" is spelled P-E-R-F-I-D-Y. The IPA pronunciation is /ˈpɜː.fɪ.di/.
What does "perfidy" mean?
As a noun, "perfidy" means: A state or act of violating faith or allegiance; violation of a promise or vow, or of trust.
How do you pronounce "perfidy"?
The IPA (International Phonetic Alphabet) transcription for "perfidy" is /ˈpɜː.fɪ.di/. 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 "perfidy"?
From Middle French perfidie, from Latin perfidia from perfidus (“faithless, treacherous, false”), from fides (“faith”); related to, for example, English fidelity. 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 "perfidy", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 7 letters (nearest by frequency rank).

peckish#92,987Philpot#93,004Phrygia#93,007Panmure#92,977

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

Source: FrequencyWords open word-frequency list