rapidity
/ɹəˈpɪd.ɪ.ti/
"rapidity" is a 8-letter English headword indexed on PlainSpell.
The verdict
“rapidity” is uncommon English (frequency #61,748 among 3,094 “R” headwords), classed as a noun. The kind of spelling people second-guess.
- #61,748
- frequency rank, English
- 3,094
- “R” headwords
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - speed, swiftness; the condition of being rapid
Corpus desk
Index EN-rapidity · rapidity · English
rapidity · rank #61,748 · 0 variants · 0 confusables
- FREQ-RARE #61,748
- LEN-LONG 8 letters
- VOW-4 4 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-MID 3,094
- PHOTO-FINISH Ravindra
Nearest frequency peer: Ravindra (+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 “rapidity”
Sparse band: bars invert rank so rarer forms read shorter
- ragtag
ragtag
38,255 corpus weight
- rapidity
rapidity
38,253 corpus weight
- Ravindra
Ravindra
38,252 corpus weight
- razzle
razzle
38,251 corpus weight
- RDX
RDX
38,250 corpus weight
- Reay
Reay
38,249 corpus weight
What this shows Long-tail view: where “rapidity” sits against similarly uncommon English ranks.
| Property | Value |
|---|---|
| Headword | rapidity |
| Language | English |
| Part of speech | Noun |
| IPA | /ɹəˈpɪd.ɪ.ti/ |
| Letters | 8 |
| Frequency rank | #61,748 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “rapidity” in English
Rare enough to double-check
rapidity is uncommon English at frequency #61,748 among 3,094 “R” headwords, classed as anoun, transcribed /ɹəˈpɪd.ɪ.ti/. Rarity is why readers land here mid-draft. 3 senses are on record.
No generated misspelling entries exist for rapidity in our index, suggesting the orthography follows predictable English patterns. Our confusable-pair dataset has no match for it, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.
Etymologically, the entry records: From rapid + -ity, from French rapidité, from Latin rapiditas. The correct English form is rapidity, spelled R-A-P-I-D-I-T-Y.
Definition
- 1speed, swiftness; the condition of being rapid
- 2A measure of velocity relative to the speed of light; defined as artanh(v), where artanh is the hyperbolic arctangent, and v = speed (with c = speed of light = 1).
- 3A measure of the velocity of a particle in a beam relative to the beam's axis
Recorded use
Wiktionary exampleThese source excerpts show how rapidity appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
Although appreciating the rapidity and frequency of the Southern electric services I was now to use on short journeys, I became more than ever convinced that electric traction offers very little of interest to the dyed-in-the-wool railwayist.
Etymology
From rapid + -ity, from French rapidité, from Latin rapiditas.
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 "rapidity", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 8 letters (nearest by frequency rank).