noun
Refers to a rough, violent person; often used in historical or dramatic contexts. Modern usage is somewhat literary or old-fashioned.
時代劇では、乱波が町を荒らす場面がよくある。
In period dramas, there are often scenes where ruffians rampage through the town.
彼はまるで乱波のような振る舞いだった。
He behaved just like a thug.
noun
Archaic term for a spy or undercover agent, historically associated with ninja or covert operatives. Related to 素っ破 (すっぱ).
See also: 素っ破 (すっぱ)
戦国時代、乱波は敵の情報を探るために雇われた。
During the Warring States period, spies were hired to gather enemy intelligence.
Also an archaic term for a spy; 乱波 and 素っ破 are closely related, with 素っ破 being a more common reading for the spy sense.
The derivation is uncertain. The kanji 乱 (disorder) and 波 (wave) may suggest a disruptive or covert figure, but the exact origin is unclear.