perfidious
/pɚˈfɪdi.əs/
"perfidious" is a 10-letter English headword indexed on PlainSpell.
The verdict
“perfidious” is uncommon English (frequency #85,638 among 4,417 “P” headwords), classed as an adjective. The kind of spelling people second-guess.
- #85,638
- frequency rank, English
- 4,417
- “P” headwords
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Of, pertaining to, or representing perfidy; disloyal to what should command one's fidelity or allegiance.
Corpus desk
Index EN-perfidious · perfidious · English
perfidious · rank #85,638 · 0 variants · 0 confusables
- FREQ-RARE #85,638
- LEN-MEGA 10 letters
- VOW-5 5 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-MID 4,417
- PHOTO-FINISH perdita
Nearest frequency peer: perdita (-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 “perfidious”
Sparse band: bars invert rank so rarer forms read shorter
- penton
penton
14,366 corpus weight
- penury
penury
14,365 corpus weight
- perdita
perdita
14,364 corpus weight
- perfidious
perfidious
14,363 corpus weight
- perianth
perianth
14,362 corpus weight
- pern
pern
14,360 corpus weight
What this shows Long-tail view: where “perfidious” sits against similarly uncommon English ranks.
| Property | Value |
|---|---|
| Headword | perfidious |
| Language | English |
| Part of speech | Adjective |
| IPA | /pɚˈfɪdi.əs/ |
| Letters | 10 |
| Frequency rank | #85,638 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “perfidious” in English
Rare enough to double-check
perfidious is uncommon English at frequency #85,638 among 4,417 “P” headwords, classed as anadjective, transcribed /pɚˈfɪdi.əs/. Rarity is why readers land here mid-draft. Gloss: "Of, pertaining to, or representing perfidy; disloyal to what should command one's fidelity or allegiance.".
Zero misspellings are on record for perfidious in our index, and the word's spelling is regular enough that our generator found nothing worth flagging. This headword has no recorded confusable partner, which typically means the spelling is too distinctive to be mistaken for another word.
Etymologically, the entry records: From Latin perfidiōsus (“treacherous”), from perfidia. The correct English form is perfidious, spelled P-E-R-F-I-D-I-O-U-S.
Definition
- 1Of, pertaining to, or representing perfidy; disloyal to what should command one's fidelity or allegiance.
Recorded use
Wiktionary examplesThese source excerpts show how perfidious appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
TRINCULO (speaking about Caliban): By this light, a most perfidious and drunken / monster: when his god's asleep, he'll rob his bottle.
The perfidious Ricimer soon became dissatisfied with Anthe'mius, and raised the standard of revolt.
Etymology
From Latin perfidiōsus (“treacherous”), from perfidia.
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
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Similar English words by spelling shape
Same letter count and similar misspelling depth for "perfidious", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 10 letters (nearest by frequency rank).