black metal

Short definition from Wiktionary

Noun

1. 1
   Iron, or similar metals worked by a blacksmith
2. 2
   A subgenre of heavy metal music employing fast tempos, shrieked vocals, highly distorted guitars, double-kick drumming, raw recording and unconventional song structure, often emphasizing antireligious and misanthropic themes.
3. 3
   Any form of extreme metal having a Satanic or anti-Christian theme.