Rare, literary term for a military incursion or attack. Modern Japanese normally uses 侵略 (しんりゃく) or 襲撃 (しゅうげき).
Ancient documents record invasions from foreign lands.
The derivation is uncertain; the kanji 来 (come) and 冦 (invade) suggest a compound meaning 'coming to invade'. The word is not in common modern use.