Nebulous (adjective)

1. Vague, unclear, or ill-defined, lacking a definite form or shape.
2. Hazy, cloudy, or misty.

Origin:

From the latin word nebula meaning "cloud" or "mist".

Examples:

1. The plan was nebulous and lacked specific details.
2. His ideas were nebulous and never came to fruition.
3. The future looked nebulous and uncertain.
4. The nebulous clouds obscured the view of the mountains.
5. The nebulous concept was hard to grasp.