Abarim Publications' online Biblical Hebrew Dictionary
פוך
The rootless masculine noun פוך (puk), is probably a foreign loan word (suggests BDB Theological Dictionary) and possibly related to an Arabic verb that means to open or separate, and to a Syriac verb that means to pulverize.
In the Bible our noun carries the meaning of antimony or stibium; a black mineral powder used for eye make-up. It occurs a mere few times: 2 Kings 9:30, 1 Chronicles 29:2, Jeremiah 4:30, Isaiah 54:11, and in the name Keren-happuch.