noun which may take the genitive case particle 'no', noun
for self-defense; for self-protection
Used as a noun or no-adjective to describe items, techniques, or measures intended for personal protection.
彼女は護身用にスプレーを持ち歩いている。
She carries a spray for self-defense.
護身用の技術を習う。
Learn self-defense techniques.
Compound of 護身 (goshin, 'self-protection') and 用 (yō, 'for use'). The exact historical derivation is straightforward.