From WordNet (r) 2.0 (August 2003) [wn]:
sketchy
adj : giving only major points; lacking completeness; "a sketchy
account"; "details of the plan remain sketchy" [syn:
unelaborated]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Sketchy \Sketch"y\, a.
Containing only an outline or rough form; being in the manner
of a sketch; incomplete.
[1913 Webster]
The execution is sketchy throughout; the head, in
particular, is left in the rough. --J. S.
Harford.
[1913 Webster]