A derogatory name for bands and music relating to the "nu-metal" genre. The expression is supposed to give off the connotation that it is not as heavy as true metal and often made from old, recycled material. However, keep in mind such phrases are commonly misused.

Can be referred to as an object used to beat someone down with, especially a baseball bat, like the ones used in Major League Baseball.

A genre of music. More so, a sub-genre of the Rock category that falls between alternative and metal.

Scale from softest->hardest.
Soft rock - Emotional - Alternative - ALUMINUM - Hard Rock - Metal/Death Metal - Screamo.

SOFT ROCK relies on slow melody, and serenity in the vocals. Soft Rock frequently uses intruments that would not normally be used in rock music, like pianos, and acoustic instruments. Soft Rock is praised for its simultaneous simplicity, and complexity.
-Jack Johnson, The Beach Boys.

EMOTIONAL does not require a serene vocalist, but its stress is all vocal, and very little instrumental. Emotional music usually utilizes a vocalist with a high-pitch or "whiny" voice, that is not particularly skillful at pitch, harmony, tune.
-My Chemical Romance, All American Rejects, Saosin.

ALTERNATIVE is very broad, so many bands have been pushed in because they don't have their own genre so they call them "Alternative." Alternative bands qualify as alternative for their earthy vocals and mediocre instrument stress. Most alternative bands rely heavily on their singer to disguise their lack of instrumental talent. Sadly... There is little instrumental stress, usually. Most of the stress is vocal.
-Creed, Matchbox 20.

HARD ROCK employs heavy distorted electrical guitar riffs paired with powerful vocals. The only reservation hard rock has, is screaming. They still sing. Though screaming is not forbidden, and is justified in the movement of the intensity o...