MI5
"mi5" is a 2-letter English headword indexed on PlainSpell.
The verdict
“MI5” sits in 20 confusable pairs (corpus #33,328) as a proper noun. The look-alike neighbours are the real trap.
- #33,328
- frequency rank, English
- 4,057
- “M” headwords
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed September 2, 2026) - The domestic intelligence and counter-espionage agency of the United Kingdom, which operates in secret and whose primary function is to spy on terrorist organizations and others viewed as a threat ...
Corpus desk
Index EN-mi5 · MI5 · English
MI5 · rank #33,328 · 0 variants · 20 confusables
- FREQ-MID #33,328
- LEN-MID 3 letters
- VOW-1 1 vowel
- CONFUS-HIGH 20 pairs
- VAR-0 0 variants
- BOOK-MID 4,057
- PHOTO-FINISH Metcalf
Nearest frequency peer: Metcalf (-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.
Frequency neighbourhood for “MI5”
Lower corpus rank = more everyday usage (inverted bar length for readability)
- Maura
Maura
66,677 corpus weight
- mecha
mecha
66,675 corpus weight
- Metcalf
Metcalf
66,674 corpus weight
- MI5
MI5
66,673 corpus weight
- milled
milled
66,671 corpus weight
- Miocene
Miocene
66,670 corpus weight
What this shows Bars show where “MI5” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.
Visual similarity to commonly confused words
How many letter changes separate each confused pair (Levenshtein distance, normalized).
Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).
| Property | Value |
|---|---|
| Headword | MI5 |
| Language | English |
| Part of speech | Proper noun |
| Letters | 3 |
| Frequency rank | #33,328 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “MI5” sits in English frequency
Easy to mix with look-alikes
The spelling risk for MI5 is neighbouring look-alikes ("my", "Mr", …), not just typos; it is aproper noun. Frequency #33,328 among 4,057 “M” headwords. Gloss: "The domestic intelligence and counter-espionage agency of the United Kingdom, which operates in secret and whose primary function is to spy on terrorist organizations and others viewed as a threat ...".
No generated misspelling entries exist for MI5 in our index, and the word's spelling is regular enough that our generator found nothing worth flagging. It also participates in 20 confusable-pair relationships, "my", "Mr", "MS", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.
Etymologically, the entry records: Abbreviation of Military Intelligence, Section Five. The correct English form is MI5, spelled M-I-5.
Definition
- 1The domestic intelligence and counter-espionage agency of the United Kingdom, which operates in secret and whose primary function is to spy on terrorist organizations and others viewed as a threat to British national security. Formally known as the Security Service.
Recorded use
Wiktionary exampleThese source excerpts show how MI5 appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
The service aggressively maintained its position until I produced evidence proving it was untrue - including a recording of one of the calls with a senior MI5 officer.
Etymology
Abbreviation of Military Intelligence, Section Five.
Synonyms
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.
PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of September 2, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.
Frequently Asked Questions
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Similar English words by spelling shape
Same letter count and similar misspelling depth for "MI5", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 3 letters (nearest by frequency rank).
Data Source
Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.