Quaternary
/ˈkwɒtərˌnɛri/noun
Relating to the number four, or to the fourth in a series; also, in geology, the most recent major period of Earth’s history.
Did you know?Quaternary descends from Latin words built on quattuor, and that same ancient root also gave English words like quartet, quarter, and even pattern-shifting scientific terms across Europe.
Etymological Timeline
Proto-Indo-European
PIE
*kʷetwóres
“four”
Latin
Latin
quattuor
“four”
Late Latin
Latin
quaternarius
“consisting of four; fourfold”
Old French
Old French
quaternaire
“fourfold; relating to four”
Modern English
English
quaternary
“relating to four or the fourth in a series”