noun
half killed; beaten half to death
Describes a state of being severely beaten or injured, but not quite dead. Often used in violent or dramatic contexts.
彼は喧嘩で半殺しにされた。
He was beaten half to death in a fight.
半殺しの目にあわせてやる。
I'll beat you within an inch of your life.
殺し means 'killing' or 'murder', while 半殺し specifically means 'half-killed' or 'beaten nearly to death'.
Compound of 半 (half) and 殺し (killing), literally 'half-killing'.