Where does “sesquidecennial” come from?

sesquidecennial (English) comes from English decennial, from Latin decennialis, from Latin -ennium, from Latin -ennis, from Latin annus, from Proto-Italic atnos, from Proto-Indo-European h₂et-no-, from Proto-Indo-European h₂et- — grass.

sesquidecennial (English): Relating to a fifteen year period

Definitions

  1. Relating to a fifteen year period

Ancestry of “sesquidecennial”, step by step

StepLanguageWordMeaning
1EnglishdecennialThe tenth anniversary of an event or happening;...
2Latindecennialis—
3Latin-enniumforming periods of years
4Latin-ennis—
5Latinannusyear; time; season
6Proto-Italicatnosyear
7Proto-Indo-Europeanh₂et-no-—
8Proto-Indo-Europeanh₂et-grass
Every word from Proto-Indo-European h₂et- →Every word from Proto-Indo-European h₂et-no- →Every word from Proto-Italic atnos →