horror involves crimes, killings, etc, thrillers don't necessarily do so, they just keep you very interested:
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thrill·er
Function:
noun
Inflected Form(s):
-s
Etymology:
thriller from
1thrill + -er; thriller-diller from
thriller + -diller (as in
killer-diller)
: one that produces
thrills ;
especially :
a work of fiction or drama designed to hold the interest by the use of
a high degree of action, intrigue, adventure, or suspense
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