noun
making someone wait; keeping in suspense
Often used for pets made to wait before eating, or for people kept in anticipation. Common in the phrase お預けを食う (to be made to wait).
犬に「待て」と言って、お預けの状態にした。
I told the dog 'wait' and made it wait before eating.
彼はデートの約束をドタキャンされて、お預けを食った気分だ。
He feels like he's been left hanging after his date canceled at the last minute.
noun
Used for plans, decisions, or events being delayed. Slightly colloquial; 延期 is more formal.
旅行の計画は今はお預けだ。
The travel plans are on hold for now.
昇進の話はお預けになった。
The promotion talk has been postponed.
延期 is a formal term for postponement. お預け is more casual and often implies a personal, sometimes teasing, delay.
待たせる is the verb 'to make someone wait'. お預け is the noun form for the state of being made to wait, often with a nuance of suspense.
From the polite prefix お + 預け, the noun form of 預ける (to leave something in someone's care). Originally referred to leaving something with someone, then developed the sense of 'keeping someone waiting' from the idea of holding something back.