1. (adj)cloudy, nebulose, nebulous lacking definite form or limits
"gropes among cloudy issues toward a feeble conclusion"- H.T.Moore; "nebulous distinction between pride and conceit"
2. (adj)nebular, nebulous of or relating to or resembling a nebula "the nebular hypothesis of the origin of the solar system"
3. (adj)nebulous, unfixed lacking definition or definite content "nebulous reasons"; "unfixed as were her general notions of what men ought to be"- Jane Austen