have no idea
mooncalf
wrong end of the stick
misconception
misken
thought bubble
misconceiving
throw out
demented
take for
misperceive
faultily
mishear
misassumption
counteridea
misinterpret
see
misdiscern
mismean
misclaim
misimplication
undeceived
mispick
under the impression
disabused
miscomprehend
clear up
misapprehend
misbrief
misplan
put two and two together and make five
misassume
uninformedly
misguidingly
misestimate
wrongmindedness
miscalculate
misexpound
pervert
notionlessness
false step
misexplicate
fudge
ass-backwards
confuse
malobservation
misimputation
delusion
hallucination
misconceivedly