In an interview for Eddie Trunk , Geezer Butler recalled the first time someone used the term "heavy metal" to refer to Black Sabbath – and it wasn't in a complimentary way.
Like many labels that start out as one thing and are later embraced by a community and change meaning, the expression "heavy metal" was initially used pejoratively, at least in the case of Sabbath.
“When we were touring the United States – I think it was our second tour there – I read this review where the guy said, ‘This isn’t music; it sounds like a bunch of heavy metal being smashed against each other,’” Butler recounts (transcription via Loudwire ).
“Somehow, it got around England and became a sarcastic thing that people applied to us – ‘this isn’t music, it’s just a bunch of heavy metal being smashed’. And, for some reason, we got stuck with it.”
It is not yet known for certain who coined the term "heavy metal," but it is believed to have started appearing in the early 1960s, eventually becoming the title of a book called Featuring the Human Host and the Heavy Metal Kids , which was referenced in the 1968 song "Born to Be Wild" by Steppenwolf .