(also poleaxe)
Definition of poleax
noun
a short-handled ax with a spike at the back, formerly used in naval warfare for boarding, resisting boarders, and cutting ropes. a butcher’s ax with a hammerhead at the back, used to slaughter animals.
verb
[with object] hit, kill, or knock down with or as if with a poleax. cause great shock to (someone):I was poleaxed by this revelation