dream up

listen to the pronunciation of dream up
English - English
To have an imaginative, unusual or foolish idea, to invent something unreal

I am not arguing that I can dream up any reality I like. - John Louis Lucaites, Celeste Michelle Condit, Sally Caudill: Contemporary Rhetorical Theory.

devise or invent; "He thought up a plan to get rich quickly"; "no-one had ever thought of such a clever piece of software"
If you dream up a plan or idea, you work it out or create it in your mind. I dreamed up a plan to solve both problems at once His son hadn't dreamed it up
think up, conceive, invent, devise, imagine, picture, envisage
dream up