quatercentennial

[ kwot-er-sen-ten-ee-uh l ]
/ ˌkwɒt ər sɛnˈtɛn i əl /

adjective

pertaining to or marking a period of 400 years.

Origin of quatercentennial

1960–65; < Latin quater four times + centennial
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019