(Adjective) Vague, indistinct, formless, ill-defined.

In Context

“Creativity is a rather nebulous concept encapsulating all these human characteristics and skills – seen by some as  innate and by others as learned – that involve the ability to see things in a new way; to invent new ideas, concepts, and objets; and to provide new associations between existing entities.”

Sarah Kember and Joanna Zylinska, Life after New Media: Mediation as a Vital Process, 2012.