Ill-defined
Part of speech: adjective
Definition: Poorly defined; blurry, out of focus; lacking a clear boundary.
Unclear
Part of speech: adjective
Definition: Ambiguous; liable to more than one interpretation.Not clearly or explicitly defined.Not easy to see or read; indecipherable or unreadable.
Example sentence: Well, it was very interesting to play a character and stretch it over such a long time - 12 episodes. I had never done a TV show before, so week to week it was unclear what we would be asked to do.