拘束
こうそく · kousoku · JLPT N3 · noun
restriction
⛓️ 拘束 = seize (拘) + bind in a bundle (束): held and tied down
拘 also appears in 拘留 (detention), and 束 is the bundle in 花束 (bouquet). Together they mean being seized and bound. Don't confuse it with its homophone 高速 (こうそく, high speed), which means the opposite of being held back.
束 — 木 (tree) with 口 wrapped around middle
Pictograph of a bundle: a tree or sticks (木) tied together with a band or rope (depicted by the enclosing 口 in the middle). The original sense was 'to bind' or 'a bundle,' which extended to meanings like 'to restrain,' 'to control,' and the measure word for bundled things.