noun, na-adjective
Bound form used mainly in compounds and set phrases; not a free-standing word. Cross-referenced with 暴を以て暴に易う is a classical expression meaning 'to replace violence with violence'.
See also: 暴を以て暴に易う
「暴を以て暴に易う」という古い言い回しがある。
There is an old expression, 'replace violence with violence'.