A thing that looks good on paper but is useless in reality; an impractical idea or pie-in-the-sky plan.
給料が増えると言われただけでは、行動が伴わなければ絵に描いた餅だ。
Unless actions follow the promise of higher pay, it's just a pie-in-the-sky.
彼の理想論は素晴らしいが、現実性がないので絵に描いた餅だ。
His idealism is admirable, but it's impractical, just a pipe dream.
口先だけの約束は絵に描いた餅で、信用を失う原因になる。
Promises without follow-through are pie-in-the-sky and can cause you to lose trust.