Where does “bi-hourly” come from?

bi-hourly (English) comes from English hourly, from English hour, from Middle English houre, from Old French houre, from Latin hōra, from Ancient Greek ὥρα, from Proto-Hellenic *worā, from Proto-Indo-European wēr- — to burn; to cover, heed, notice; squirrel.

Ancestry of “bi-hourly”, step by step

StepLanguageWordMeaning
1EnglishhourlyOccurring every hour; Unsalaried, paid by the...
2EnglishhourA time period of sixty minutes; one twenty-fourth...
3Middle Englishhourehour; A time, occasion, or moment; A canonical...
4Old Frenchhourehour; time; moment to do something
5Latinhōrahour
6Ancient Greekὥραany defined period of time; season; climate
7Proto-Hellenic*worā
8Proto-Indo-Europeanwēr-true
9Proto-Indo-Europeanwer-to burn; to cover, heed, notice; squirrel
Every word from Proto-Indo-European wer-