Heavy metal music
Critics disagree over who can be thought of as the first heavy metal band. Most credit either Led Zeppelin or Black Sabbath, with American commentators tending to favour Led Zeppelin and British commentators tending to favour Black Sabbath, though many give equal credit to both. A few commentators—mainly American—argue for other groups including Iron Butterfly, Steppenwolf or Blue Cheer. Deep Purple, the third band in what is sometimes considered the "unholy trinity" of heavy metal (Black Sabbath, Led Zeppelin, and Deep Purple), despite being slightly older than Black Sabbath and Led Zeppelin, fluctuated between many rock styles until late 1969 when they took a heavy metal direction.
Heavy metal music
Metal historian Ian Christe describes what the components of the term mean in "hippiespeak": "heavy" is roughly synonymous with "potent" or "profound," and "metal" designates a certain type of mood, grinding and weighted as with metal. The word "heavy" in this sense was a basic element of beatnik and later countercultural hippie slang, and references to "heavy music"—typically slower, more amplified variations of standard pop fare—were already common by the mid-1960s, such as in reference to Vanilla Fudge. Iron Butterfly's debut album, released in early 1968, was titled "Heavy". The first use of "heavy metal" in a song lyric is in reference to a motorcycle in the Steppenwolf song "Born to Be Wild", also released that year: "I like smoke and lightning/Heavy metal thunder/Racin' with the wind/And the feelin' that I'm under."