Formal:
* Her plans for the future were nebulous, lacking any concrete details.
* The company's vision statement was so nebulous that it was difficult to understand what they actually aimed to achieve.
* The government's response to the crisis was nebulous, leaving the public confused and anxious.
Informal:
* I have a nebulous feeling that something bad is going to happen.
* Her reasons for breaking up with him were nebulous at best.
* The plot of the movie was so nebulous that I couldn't follow it.
Creative:
* His memories of childhood were nebulous, like wisps of smoke fading into the air.
* The artist's abstract paintings captured the nebulous nature of human emotions.
Note: "Nebulous" often implies a lack of clarity or definition. It can be used to describe ideas, plans, concepts, feelings, or even memories.