Metal
Metal, Adj.:
1. Music normally played at a loud volume, with fast tempos, extrodinary guitar, solid bass, and a strong drum beat (drumming is normally played with double bass drums). Metalheads normally start out listening to Iron Maiden, Metallica, Judas Priest, Black Sabbath, etc. But from the point where one starts listening to "heavy" music, one's insatiable thrist for metal cannot be quenched. So, much like a drug, listeners get adicted, and they look for heavier and faster bands, such as: Death, Venom, Slayer, Sodom, Motorhead, and Pantera. Most don't dare go beyond this group of bands, for fear of geting their fucking heads blown off. But, some do still persue yet heaver bands such as: Napalm Death, Kreator, Pig Destroyer, Cannibal Corpse, and the infamous Mayhem.

Metal, Noun or Verb: 
2. Usually replacing "cool", "awesome", or other words such as that, which are "extreme". For instance, "Holy shit dude, that was so fucking metal!" 
"metal" can also be a verb, such as, "lets go do somthing metal", which means "lets go do somthing fun or exciting".

"Now thats metal!"
               -Sebastian Bach
"Oh man... that... was so metal"
"Ok, lets go listen to some metal"
When Zakk Wylde was asked to discribe metal, he anwsered with a long swig of his pale ale, a respectfull huff, and a, "Metal.... is... metal"