dream up

US /ˌdriːm ˈʌp/
UK /ˌdriːm ˈʌp/
"dream up" picture
1.

思いつく, 考案する, 夢想する

to invent something in your mind, especially something unusual or impractical

:
He dreamed up a crazy plan to travel around the world in a hot air balloon.
彼は熱気球で世界一周するという奇抜な計画を思いついた
Where did you dream up that ridiculous idea?
そのばかげたアイデアはどこで思いついたの?