adverb
alternately; every other one
Used when selecting or arranging items at intervals of one, i.e., skipping one between each chosen item. Often used with nouns like 日 (day), 人 (person), or 席 (seat).
See also: 一つ置き
この薬は一つ置きに飲んでください。
Please take this medicine every other day.
一つ置きに席に座ってください。
Please sit in every other seat.