1
general::
Phrase(s): on the shelf
1. Fig. not active socially; left to oneself in social matters. (Alludes to being left or stored on a shelf.) • I’ve been on the shelf long enough. I’m going to make some friends. • She likes being on the shelf. 2. Fig. postponed. • We’ll have to put this matter on the shelf for a while. • I have a plan on the shelf just waiting for an opportunity like this.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Inactive, not employed, as in With mandatory retirement at 65, many useful employees are put on the shelf. [Second half of 1500s] 2. In a state of disuse, as in We'll have to put her proposal on the shelf until we have more funds. [Late 1800s] 3. Without prospects of marriage. For example, After she broke her third engagement, her parents were sure she'd be on the shelf. This usage is always said of a woman and today considered offensive. It is probably obsolescent. [Early 1800s] All these usages allude to an article left on the shelf of a store, bookcase, or the like.
American Heritage Idioms