 Another popular etymology is the hypothetical Greek word <unk> <unk> , " against <unk> " , explained as " not found as metal " , or " not found <unk> " . <unk> conjectured a hypothetical Greek word <unk> <unk> , which would mean " <unk> " , and cites several examples of related Greek words ( but not that one ) which describe chemical or biological <unk> . 
