A3

noun

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

"a3" is a 1-letter English headword indexed on PlainSpell.

The verdict

“A3” is a moderately-common English word, ranked #19,748 in English word frequency and used as a noun.

#19,748
frequency rank, English
2
letters
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A one-page document, often tabular or graphical, on such paper.

Visual similarity to commonly confused words

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

A3 vs as
0% similar
A3 vs at
0% similar
A3 vs an
0% similar

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

Key facts for A3
PropertyValue
HeadwordA3
LanguageEnglish
Part of speechNoun
Letters2
Frequency rank#19,748
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Where “A3” 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). A3 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 A3 is 2 letters long, classified as a noun. Corpus data places it at rank #19,748 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 2 distinct senses for this headword, so context determines which meaning a reader should apply.

A3 doesn't appear in our generated misspelling index, a sign its spelling follows regular English conventions. It also participates in 20 confusable-pair relationships, "as", "at", "an", and more, a pairing that trips writers up because the two words share enough sound or shape to blur together.

Etymologically, the entry records: See the Wikipedia article ISO 216, the international standard on paper sizes. The correct English form is A3, spelled A-3.

Definition

  1. 1
    A one-page document, often tabular or graphical, on such paper.
  2. 2
    A3 class, a class of steam locomotive used on the London and North Eastern Railway.

Etymology

See the Wikipedia article ISO 216, the international standard on paper sizes.

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 "A3"?
"A3" is spelled A-3.
What does "A3" mean?
As a noun, "A3" means: A one-page document, often tabular or graphical, on such paper.
What words are commonly confused with "A3"?
"A3" is commonly confused with "as", "at", "an". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
What is the origin of the word "A3"?
See the Wikipedia article ISO 216, the international standard on paper sizes. See the full etymology section above for more details.
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 “A3”

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

  • The one correct English spelling is A-3 - every other letter order is a misspelling in standard orthography.
  • Don't mix it up with “as” - see the side-by-side comparison. A3 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