Where does “sesquicentennially” come from?

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

sesquicentennially (English): Celebrated after 150 years

Definitions

  1. Celebrated after 150 years

Ancestry of “sesquicentennially”, step by step

sesquicentennially traces back through two separate lines of ancestry.

via English sesquicentennial

StepLanguageWordMeaning
1EnglishsesquicentennialOccurring every 150 years; Of, or relating to a...
2EnglishcentennialRelating to, or associated with, the...
3English-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
4Middle English-al
5Old French-alsuffix used to form adjectives from nouns
6Latin-ālis
7Proto-Italic-ālisforms relational adjectives

via English ly

StepLanguageWordMeaning
1EnglishlyAbbreviation of light-year
2VietnameselyAlternative spelling of li
Every word from Proto-Italic -ālisEvery word from Latin -ālisEvery word from English -ál