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PlainSpell

arity

/ˈæɹɪti/noun

arity is a noun meaning “The number of arguments or operands a function or operation takes. For a relation, the number of domains in the corresponding Cartesian product” (English Wiktionary, September 2026). It is spelled A-R-I-T-Y, and it appears about once in every 28 million words in written English (wordfreq, 2021 data). The plural of arity is arities.

What does arity mean?

noun

  1. 1

    The number of arguments or operands a function or operation takes. For a relation, the number of domains in the corresponding Cartesian product.

  2. 2

    The maximum number of child nodes that any node in a given tree (data structure) may have.

  3. 3

    the number of arguments (in Lojban grammar called sumti) specified in the definition of a selbri. (the selbri combined with the sumti make up a bridi).

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

How do you pronounce arity?

  • /ˈæɹɪti/
  • /ˈeəɹɪti/

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-us-arity.ogg, Wikimedia Commons (author and licence on each file's page).

Forms of arity

  • arities plural

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

How common is arity?

Arity appears about once in every 28 million words in written English, the 159,707th most frequent word form in the list.

Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

Arity in Spanish, French, German and Portuguese

In the sense number of arguments:

LanguageWords
Frencharité
GermanStelligkeit
Portuguesearidade
Spanisharidad

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

Where does arity come from?

From -ary (taken from unary/binary/ternary [function/operator]) + -ity. Compare adicity and adinity.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).