APIvsassWhat's the difference?

Which to use

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

#11,501
“API” frequency rank
#1,065
“ass” frequency rank
12566
confusion score

Side-by-Side Comparison

Feature API ass
Definition Initialism of active pharmaceutical ingredient. Any of several species of horse-like animals, especially Equus asinus, the domesticated of which are used as beasts of burden.

Where the eye mixes API and ass

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

3 ch
API
3 ch
ass

Why the eye confuses API with ass

A purely visual mix-up. API (/ˌeɪˌpiˈaɪ/) and ass (/æs/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 12566, derived from the frequency rank of both members and their visual similarity.

API is recorded at frequency rank #11,501, classified as anoun, pronounced /ˌeɪˌpiˈaɪ/. ass is at rank #1,065, tagged as anoun, pronounced /æs/.

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 12566, this pair ranks #480,813 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of API vs ass

Shared letters: a. Private to "API": ip. Private to "ass": s.

"API" · 3 letters · shape VCV  ·  "ass" · 3 letters · shape VCC

Frequently Asked Questions

Is swapping "API" for "ass" ever safe?
No. They are said differently (/ˌeɪˌpiˈaɪ/ versus /æs/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
In ordinary English text, does "API" or "ass" show up more?
"ass" is the more common of the two: it sits at frequency rank #1,065 in our English list, against #11,501 for "API". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Eye-level mix-up between "API" and "ass" is sorted above. Next: full entries or other pairs that share a letter shape.

  • Full dictionary entry for "API" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "ass" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #480,813 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "API" and "ass" also get mixed up with nearby pairs, the highest-scored neighbour is "amb vs API". Nearby pair

Confusion rank #480,813 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