Where does “quadracentennial” come from?

quadracentennial (English) comes from English centennial, from English -ál, from Middle English -al, from Old French -al, from Latin -ālis, from Proto-Italic -ālis — forms relational adjectives.

Ancestry of “quadracentennial”, step by step

StepLanguageWordMeaning
1EnglishcentennialRelating to, or associated with, the...
2English-álOf or pertaining to. Adjectival suffix appended to various words, often nouns, to produce an adjective form. Often added to words of Latin origin, but used with other words also
3Middle English-al
4Old French-alsuffix used to form adjectives from nouns
5Latin-ālis
6Proto-Italic-ālisforms relational adjectives
Every word from Proto-Italic -ālisEvery word from Latin -ālisEvery word from English -ál