every other one; alternate
Used as a noun or adverbially to describe spacing or selection where one item is skipped between each chosen item. Often follows a counter or noun indicating the interval.
On this street, there is a streetlight at every other interval.
He sat in every other seat.
Please arrange the chairs with one space between each.
Please sit with one seat empty between each person as a precaution against infection.
I marked every other line with a check.