miss one's guess
misassumption
under the impression
misassume
misfigure
incorrectness
misexplicate
given
precondition
presumption
ring false
misclaim
put two and two together and make five
misinterpret
misdistinguish
misimagine
misunderstanding
mistaking
misinterpretation
missuppose
misconclusion
misperceive
misimplication
assuming
misformulate
misexplication
misexplain
misderive
misprognosticate
thought bubble
misdiscern
misexpound
have no idea
misunderstand
petitionarily
wrong end of the stick
take for
misinfer
misexpress
thonk
through the wrong end of the telescope
misperception
ass-backwards
not done
illusion
unright
mispick
mistaken
misgather
misguided