You can't work out this project with nebulous plans in mind.

Solution (By Examveda Team)

Nebulous : in the form of a cloud or haze; hazy; obscure.
Useful : able to be used for a practical purpose or in several ways.
Practical : of or concerned with the actual doing or use of something rather than with theory and ideas.
Clear : (of a substance) transparent; unclouded.
Fundamental : forming a necessary base or core; of central importance.

Antonym of Nebulous is Clear