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1.
Derived from the hardcore and emo (emotion), heartcore is anyone/anything that is hard-hittingly and emotionally heartful. I.E.- Heartcore music is a mix of raw, emotional and somewhat melodic lyrics with thrashing guitar, bass, and drums as well as any other eclectic instrument added into the mix.
Unfortunately, The Used is described as heartcore. View heartcoreclothing.com. From Autumn to Ashes is an excellent example of Heartcore.
by Heather... April 07, 2004
 
2.
Hardcore and emo. Hardcore music that is very heartfelt.
www.heartcore-emo.org . Mine.
by Becky May 30, 2004
 
3.
hardcore, emo.

like has a screamer as the lead vocalist, and has a melodic singer for points or chorus.
from autumn to ashes, atreyu, as cities burn, funeral for a friend, he is legend
by XAlexX August 08, 2005
 
4.
first off, the postal service and catch 22 are not in any way shape or form "heartcore."

the other deff that no one has mentioned is the clothing company that specializes in shirt graphics.

often favored by sceney boppers and emo kids.
person1: hey, thats a cute shirt. whered you get it?
person2: its heartcore. i got it on their website.
person1: oh cool. is that a dinosour or a llama?
person2: im not sure.... but its cute tho, right?
person1: totally.
by ghettostarchild August 15, 2007
 
5.
new found name for emo, heartfelt and hardcore
The Early November, The StoryBook Ending, Funeral For a Friend
by Nell April 10, 2004
 
6.
Insane music. The Postal Service, Catch 22.
by Joe the MOFO October 04, 2003