RBF
"rbf" is a 3-letter English headword indexed on PlainSpell.
The verdict
“RBF” is uncommon English (frequency #77,126 among 3,094 “R” headwords), classed as a noun. The kind of spelling people second-guess.
- #77,126
- frequency rank, English
- 3,094
- “R” headwords
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Abbreviation of rat-bite fever.
Corpus desk
Index EN-rbf · RBF · English
RBF · rank #77,126 · 0 variants · 0 confusables
- FREQ-RARE #77,126
- LEN-MID 3 letters
- VOW-0 0 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-MID 3,094
- PHOTO-FINISH readymade
Nearest frequency peer: readymade (+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 “RBF”
Sparse band: bars invert rank so rarer forms read shorter
- Ramachandran
Ramachandran
22,878 corpus weight
- RBF
RBF
22,875 corpus weight
- readymade
readymade
22,874 corpus weight
- reappointme…
reappointment
22,873 corpus weight
- recordkeepi…
recordkeeping
22,872 corpus weight
- rectitude
rectitude
22,871 corpus weight
What this shows Long-tail view: where “RBF” sits against similarly uncommon English ranks.
| Property | Value |
|---|---|
| Headword | RBF |
| Language | English |
| Part of speech | Noun |
| Letters | 3 |
| Frequency rank | #77,126 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “RBF” in English
Rare enough to double-check
RBF is uncommon English at frequency #77,126 among 3,094 “R” headwords, classed as anoun. Rarity is why readers land here mid-draft. 3 senses are on record.
We couldn't generate a plausible misspelling set for RBF, which points to an orthography that plays by predictable English rules. This headword has no recorded confusable partner, which tends to mean the word is visually distinctive enough to stand on its own.
No explicit etymology string is stored for this entry, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is RBF, spelled R-B-F.
Definition
- 1Abbreviation of rat-bite fever.
- 2Abbreviation of radial basis function, a type of equation used to approximate a vector field, used in neural networks.
- 3Abbreviation of resting bitch face.
Recorded use
Wiktionary examplesThese source excerpts show how RBF appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
"When I first met you I was scared of you." This phrase is commonplace for people with an RBF. They come to accept the natural state of their face as one that exudes feelings of anger, disgust or misery.
Her RBF has been with her ever since she was a baby, forcing her to fake a smile all the time so people would stop questioning her.
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 "RBF", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 3 letters (nearest by frequency rank).