castervsclusterWhich spelling fits?

Which to use

“caster” and “cluster” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#25,312
“caster” frequency rank
#7,206
“cluster” frequency rank
32518
confusion score

Side-by-Side Comparison

Feature caster cluster
Definition Someone or something that casts. A bunch or group of several discrete items that are close to each other.

Where the eye mixes caster and cluster

Muted = shared; highlighted = the visual trap. They share 5 letters in sequence.

6 ch
caster
7 ch
cluster

Why the eye confuses caster with cluster

A purely visual mix-up. caster (/ˈkɑːstə(ɹ)/) and cluster (/ˈklʌstə/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ by 1 letter(s) in length. Our composite confusion score for this pair is 32518, derived from the frequency rank of both members and their visual similarity.

caster is recorded at frequency rank #25,312, classified as anoun, pronounced /ˈkɑːstə(ɹ)/. cluster is at rank #7,206, tagged as anoun, pronounced /ˈklʌstə/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 32518, this pair ranks #337,124 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of caster vs cluster

Shared letters: cerst. Private to "caster": a. Private to "cluster": lu.

"caster" · 6 letters · shape CVCCVC  ·  "cluster" · 7 letters · shape CCVCCVC

Known mistypes of this pair

  • casteracster · casetr · casster · casterr · castre · castter · catser · ccaster
  • clusterccluster · clluster · clsuter · clusetr · clusster · clusterr · clustre · clustter

Frequently Asked Questions

Can "caster" and "cluster" be used interchangeably?
No. They are said differently (/ˈkɑːstə(ɹ)/ versus /ˈklʌstə/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
Which is more common, "caster" or "cluster"?
"cluster" is the more common of the two: it sits at frequency rank #7,206 in our English list, against #25,312 for "caster". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

  • Full dictionary entry for "caster" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "cluster" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #337,124 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "caster" and "cluster" also get mixed up with nearby pairs, the highest-scored neighbour is "captor vs caster". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #337,124 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list