perhaps from 5465 through the idea of hollowing out as a vessel (this metal being chiefly used for that purpose); copper (the substance, or some implement or coin made of it):

KJV-- brass, money.

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5465 chalao (khal-ah'-o);

from the base of 5490; to lower (as into a void):

KJV-- let down, strike.

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5490 chasma (khas'-mah);

from a form of an obsolete prim chao (to "gape" or "yawn"); a "chasm" or vacancy (impassable interval):

KJV-- gulf.