quadrennial

The word 'quadrennial' is a modern English formation built directly from classical Latin components. The first element, 'quadr-', originates from the Latin quattuor (four), a descendant of the Proto-Indo-European root kʷetwóres. The second element derives from Latin annus (year), from PIE h₂et-no- (year). The suffix '-ial' is a common adjectival ending from Latin -ialis. Thus, the literal construction "of or relating to a four-year period" perfectly captures its modern meanings, describing either an event recurring every four years or a duration lasting four years.

Structure: quadr (four) + enn (year) + ial (adjective suffix) - quadr: From Latin quadri- (four). A combining form indicating the number four. - enn: From Latin annus (year). The spelling is altered to 'enn' when combined. - ial: A Latin-derived adjectival suffix meaning "of or relating to".