API

/ˌeɪˌpiˈaɪ/

//ˌeɪˌpiˈaɪ// noun

By · According to Wiktionary data (CC BY-SA) ·

"api" is a 3-letter English headword indexed on PlainSpell.

The verdict

“API” is a moderately-common English word, ranked #11,501 in English word frequency and used as a noun.

#11,501
frequency rank, English
3
letters
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Initialism of active pharmaceutical ingredient.

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

API vs as
0% similar
API vs at
0% similar
API vs aw
0% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for API
PropertyValue
HeadwordAPI
LanguageEnglish
Part of speechNoun
IPA/ˌeɪˌpiˈaɪ/
Letters3
Frequency rank#11,501
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Where “API” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right). API lands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Spelling & Dictionary Insight

The English entry for API is 3 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /ˌeɪˌpiˈaɪ/. Corpus data places it at rank #11,501 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 5 distinct senses for this headword, so context determines which meaning a reader should apply.

The misspelling generator found no plausible variants for API, since its letter pattern doesn't lend itself to common typo substitutions. It also participates in 20 confusable-pair relationships, "as", "at", "aw", and more, where similar look or sound leads writers to substitute one word for another in context.

No borrowing history is documented for this entry, so its spelling is easiest to reason about phoneme by phoneme, absent a documented history. The correct English form is API, spelled A-P-I.

Definition

  1. 1
    Initialism of active pharmaceutical ingredient.
  2. 2
    Initialism of application programming interface.
  3. 3
    Initialism of Asian and Pacific Islander.
  4. 4
    Initialism of advanced primer ignition.
  5. 5
    Initialism of armor-piercing incendiary.

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

How do you spell "API"?
"API" is spelled A-P-I. The IPA pronunciation is /ˌeɪˌpiˈaɪ/.
What does "API" mean?
As a noun, "API" means: Initialism of active pharmaceutical ingredient.
What words are commonly confused with "API"?
"API" is commonly confused with "as", "at", "aw". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "API"?
The IPA (International Phonetic Alphabet) transcription for "API" is /ˌeɪˌpiˈaɪ/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What language does "API" come from?
"API" is a English word. PlainSpell covers definitions, pronunciations, and spelling data across English, Spanish, Portuguese, French, and German.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Using “API”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is A-P-I - every other letter order is a misspelling in standard orthography.
  • Say it as /ˌeɪˌpiˈaɪ/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Don't mix it up with “as” - see the side-by-side comparison. API vs as
  • Browse more English words and confusable pairs in the same reference. English words
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.

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

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list