quaternary

From the Latin quaternārius (“containing or consisting of four”), from quaternī (“four each”, “four at a time”) + -ārius (whence the English suffix -ary); compare the French quaternaire.

• (UK) IPA^(key): /kwəˈtɜː.nə.ɹi/, (rare) /ˈkwɔːt.ən.(ə.)ɹi/
• (US) IPA^(key): /ˈkwɑ.tɚˌnɛɹ.i/, IPA^(key): /ˈkwɑ.tɚˌnɛə.ɹi/

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quaternary (not comparable)

1. Of fourth rank or order

   the quaternary stress in a pronounced word

2. Of a mathematical expression containing e.g. x⁴
3. Relating to or in number base four
4. (organic chemistry) quaternary ammonium
5. (inorganic chemistry) composed of four elements

The fourth ordinal from Latin that might etymologically follow tertiary is quartary, but quaternary (from the distributive number instead) is more usual in English.

• quartal
• quartary (obsolete)

• bisquaternary
• quaternary ammonium

• quaternion

• unary, unitary (1)
  • primary (1st)
• binary (2)
  • secondary (2nd)
• ternary or trinary (3)
  • tertiary (3rd)
• quaternary (4)
  • quartary (4th)
  • tetranary (4)
• quinary (5)
• senary (6)
• septenary (7)
• octonary (8)
• novenary (9)
  • nonary (9th)
• denary (10)
• duodenary (12)
• vicenary (20)
• tricenary (30)
• sexagenary (60)
• centenary (100)

quaternary (plural quaternaries)

1. (chemistry) A quaternary compound.
2. (geology) The Quaternary period or the system of deposits laid down during it.