1.
every other ~; at intervals of ~; leaving a gap of ~
Attaches to a number-plus-counter phrase to state the size of the gap between one occurrence and the next. Because it names the gap rather than the cycle, 一日おきに means every second day, not every day. Used for gaps in time and in space alike.
Cherry trees are planted at ten-meter intervals along both sides of the road.
From 置く (to place, to leave), so the literal sense is "leaving ~ in between."
Common patterns
- 一日おきに: every other day (one day skipped)
- 一週間おきに: every two weeks
- 一行おきに: on every other line
- 一つおきに: every other one
- 三十分おきに: every thirty minutes
Similar words
- ごとに: every ~ — counts the unit itself, so 一日ごとに is every single day, while 一日おきに is every second day. With durations such as 三十分, the two come out the same, and speakers often use them interchangeably there.
Watch out
With counters of two or more, native usage is not fully consistent; 二日おきに is normally every third day, but some speakers say it for every second day. When precision matters, say 三日に一度 (once every three days) instead.
Related Words
Compare:
ごとに (every ~)