noun which may take the genitive case particle 'no'
worn across the body; crossbody
Describes bags, straps, or similar items worn diagonally across the body from one shoulder to the opposite hip.
斜め掛けのバッグが便利です。
A crossbody bag is convenient.
彼はいつも斜め掛けのカバンを使っている。
He always uses a bag worn across his body.
ショルダーバッグ is a shoulder bag, which may hang from one shoulder, while 斜め掛け specifically means worn diagonally across the body.
Compound of 斜め (diagonal) and 掛け (hanging).