English
horrorthon
From horror + -thon.
Formed from horror + -thon
Latin horreō ‘to bristle’
Latin horror ‘a bristling’
Old French horror ‘horror or terror’
Middle English horer
English horror
Today it means
noun A screening of several horror movies back to back.
Language periods are conventional ranges, not dates for this word.
Etymograph / horrorthon