Heavy metal

metallic chemical element that has a high atomic number (such as lead or mercury); type of hard rock and roll music

metals which are particularly heavy (i.e. iron, copper, etc.)

Heavy metal (sometimes referred to simply as metal) is a genre of rock music that developed in the late 1960s and early 1970s. With roots in blues-rock and psychedelic rock, the bands that created heavy metal developed a thick, heavy, guitar-and-drums-centered sound, characterized by highly amplified distortion and fast guitar solos. The All Music Guide states that "of all rock & roll's myriad forms, heavy metal is the most extreme in terms of volume, machismo, and theatricality."
See more at Wikipedia.org...

Noun
1. a metal of relatively high density (specific gravity greater than about 5) or of high relative atomic weight
(hypernym) metallic element, metal
2. loud and harsh sounding rock music with a strong beat; lyrics usually involve violent or fantastic imagery
(hypernym) rock 'n' roll, rock'n'roll, rock-and-roll, rock and roll, rock, rock music

n. heavy metal

big iron