noun
a month or older; one month behind
Refers to something that is a month past its usual or expected date, such as a late event, a delayed publication, or an item that is a month old.
月遅れの雑誌を買ってしまった。
I accidentally bought a magazine that is a month old.
今年のひな祭りは月遅れで祝う地域
In some regions, Hinamatsuri is celebrated a month later this year.
noun
back number of a monthly magazine
Specifically used for issues of a monthly publication that are from a previous month, i.e., back issues.
月遅れの号は書店で割引されていることがある。
Back issues of the monthly magazine are sometimes discounted at bookstores.