CD4
"cd4" is a 2-letter English headword indexed on PlainSpell.
The verdict
“CD4” sits in 20 confusable pairs (corpus #39,729) as a noun. The look-alike neighbours are the real trap.
- #39,729
- frequency rank, English
- 5,599
- “C” headwords
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A glycoprotein found on the surface of helper T cells and several other types of immune cells.
Corpus desk
Index EN-cd4 · CD4 · English
CD4 · rank #39,729 · 0 variants · 20 confusables
- FREQ-MID #39,729
- LEN-MID 3 letters
- VOW-0 0 vowels
- CONFUS-HIGH 20 pairs
- VAR-0 0 variants
- BOOK-DENSE 5,599
- PHOTO-FINISH CBP
Nearest frequency peer: CBP (-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 neighbours of confusable “CD4”
Peers at similar corpus weight, separate from look-alike pairs below
- castrated
castrated
60,276 corpus weight
- cava
cava
60,274 corpus weight
- CBP
CBP
60,273 corpus weight
- CD4
CD4
60,272 corpus weight
- Chapin
Chapin
60,270 corpus weight
- chipmunk
chipmunk
60,269 corpus weight
What this shows Bars place “CD4” against nearest ranked English headwords, not a reprint of the confusable-pair desk.
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 | CD4 |
| Language | English |
| Part of speech | Noun |
| Letters | 3 |
| Frequency rank | #39,729 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Corpus rank beside confusables of “CD4”
Easy to mix with look-alikes
The spelling risk for CD4 is neighbouring look-alikes ("co", "CM", …), not just typos; it is anoun. Frequency #39,729 among 5,599 “C” headwords. 2 recorded senses keep meaning in play.
Zero misspellings are on record for CD4 in our index, a sign its spelling follows regular English conventions. It also participates in 20 confusable-pair relationships, "co", "CM", "CT", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.
Etymologically, the entry records: Initialism of cluster of differentiation type 4. The correct English form is CD4, spelled C-D-4.
Definition
- 1A glycoprotein found on the surface of helper T cells and several other types of immune cells.
- 2A CD4+ helper T cell.
Recorded use
Wiktionary exampleThese source excerpts show how CD4 appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
In short, while CD4 counts can tell you where you are now, the viral load tells you where you are going.
Etymology
Initialism of cluster of differentiation type 4.
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 "CD4", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 3 letters (nearest by frequency rank).