poleaxed
From Longman Dictionary of Contemporary Englishpoleaxedpole‧axed /ˈpəʊlækst $ ˈpoʊl-/ adjective [not before noun] especially British English 1 informalSURPRISEDSHOCK very surprised and shocked I was poleaxed when I heard I’d passed the exam.2 UNCONSCIOUSunable to stand because something has hit you very hard He staggered and collapsed as if poleaxed.Examples from the Corpuspoleaxed• His face assumed the poleaxed expression I have grown used to recently.