Early 19th century; earliest use found in John Adams (1735–1826), president of the United States of America. From classical Latin sextus sixth + -ennial.
Definition of sextennial in US English:
sextennial
adjectivesɛkˈstɛnɪəl
North American Politics
Sexennial.
Origin
Early 19th century; earliest use found in John Adams (1735–1826), president of the United States of America. From classical Latin sextus sixth + -ennial.