on the shelf
US /ɑn ðə ʃɛlf/
UK /ɑn ðə ʃɛlf/

1.
被冷落, 嫁不出去
no longer considered attractive or useful, especially for marriage (often used for women)
:
•
She worried about being left on the shelf as she got older.
她担心随着年龄增长会被人冷落。
•
Many women feel pressure not to be left on the shelf.
许多女性感到不被冷落的压力。
2.
搁置, 束之高阁
not being used or considered for a long time
:
•
The old project has been sitting on the shelf for years.
那个旧项目已经搁置多年了。
•
His brilliant idea was put on the shelf due to lack of funding.
他绝妙的主意因资金不足而被搁置。