running in
"running-in" is a 9-letter English headword indexed on PlainSpell.
The verdict
“running in” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.
- Unranked
- below top-frequency English
- 10
- letters
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The operating of a new engine (especially that of a motor vehicle) at less than its normal speed until proper working has been established.
Corpus desk
Index EN-running-in · running in · English
running in · unranked · 0 variants · 0 confusables
- FREQ-UNRANKED Unranked
- LEN-MEGA 10 letters
- VOW-3 3 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-THIN "R" thin
- PHOTO-UNK Peer pending
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.
| Property | Value |
|---|---|
| Headword | running in |
| Language | English |
| Part of speech | Noun |
| Letters | 10 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “running in” in English
Rare enough to double-check
running in is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "The operating of a new engine (especially that of a motor vehicle) at less than its normal speed until proper working has been established.".
running in doesn't appear in our generated misspelling index, a straightforward case of a spelling with little room for common typos. No confusable counterpart is on file for this word, suggesting its spelling stands apart enough that readers rarely confuse it with something else.
This entry carries no recorded etymology, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is running in, spelled R-U-N-N-I-N-G- -I-N.
Definition
- 1The operating of a new engine (especially that of a motor vehicle) at less than its normal speed until proper working has been established.
Recorded use
Wiktionary examplesThese source excerpts show how running in appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
For years past Pacific locomotives of all classes have worked between Kings Cross and Cambridge, […] both in order usefully to fill in gaps in their long-distance rosters, and also for running-in purposes after overhaul. Before the war the 7.18 a.m. slow from Kings Cross to Cambridge was a regular running-in turn for express locomotives stationed at Kings…
[...] moreover, there are times of pressure when, to expedite deliveries, cars may be driven in what should otherwise be the running-in period at speeds that do them no good - and over long distances too.
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). See the methodology for how each field is sourced and updated.