variant of 紐扣|纽扣[niu3 kou4]

bond; ties (of friendship etc)

Niohuru (prominent Manchu clan)

to push a button; button (one that can be pressed to trigger an action)

decorated knob protruding from seal, allowing it to be strung on a cord

knob (e.g. handle or radio button)

push button (electric switch)

starter button; on switch