"the other day" is a pretty standard and understood phrase. It usually translates to "on a recent day". So you could say "I was talking to Rachel the other day..." which would mean "I was talking to Rachel on a recent day...".
It's been pointed out to me that I will often use the phrase "the other week" and this comment is usually followed by a judgement that that is not a phrase that is used.
My question is, what are valid time-periods that can fill in the blank in the phrase "the other _"?
Some [non-exhaustive] samples:
- the other second
- the other minute
- the other hour
- the other day
- the other week
- the other month
- the other year
- the other decade
- the other century
To me, "day" and "week" sound fine, "month" and "year" are acceptable but sound a little funny, and the rest sound completely weird.
A related question to consider that might help elucidate why some of these sound more natural than others and whether substitutes are acceptable: What are the limits of the multiplier "the other"? For example, how many days into the past can I safely refer to as "the other day"? Less than a week ago? Less than a month ago? Less than a year ago?
I'd venture to say that the phrase has a human-centered nature about it -- even if you're talking about a non-human ("the volcano erupted the other day") -- which somehow limits the bounds to being less than the lifetime of a human being. But this is purely a guess.