every other day
i take showers bidaily, alone.
Occuring twice per day, just as biannual means occuring twice per year.
The bi- prefix on bidaily means "divides into two," so that bidaily events occur twice each day.
See also bidiem. Similar to biennial whose latin bi- prefix bi- means "two," so bidiem means "every two days."
I set the task to run bidaily in crontab.