The crossword solution for the term 'PB ELEMENT' is LEAD, which is a four-letter word. LEAD is a chemical element with the symbol Pb and atomic number 82. It is a heavy metal that is denser than most common materials. LEAD has been used since ancient times, primarily for plumbing, roofing, and other construction materials. It is also used in batteries, ammunition, and radiation shielding. LEAD is toxic to humans and can cause serious health problems if ingested or inhaled.