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