Etymology From "hell of (a)", like hella (originally Northern California slang). See also Wikipedia:Hella (word).
1
Northern California, Slang Intensifier (modifies verbs); to a large extent; totally; very much.
Dude, I helluv want to go to the show with you, but I'm soooo grounded.
“[…]. This helluv hurts.” We grownups burst out laughing, and I hugged her bony adolescent shoulders.2002, Peggy Vincent, Baby Catcher: Chronicles of a Modern Midwife, page 225:
2
Northern California, Slang Intensifier (modifies adjectives); to a large degree; extremely; exceedingly.
That new girl is helluv sexy.
“We had the baby, like two minutes ago. It was helluv icy. […] Naeema was so brave, just hellabitchin', and I delivered the baby myself 'cause we have this hellafresh midwife who taught me how to do it.”2002, Peggy Vincent, Baby Catcher: Chronicles of a Modern Midwife, page 226:
1 more example
“Man, if I had never been to California and read that magazine, I would be helluv scared to come out there!”2003, Adrienne Anderson, Word: Rap, Politics and Feminism, page 14:
Oh, you goddam-betcha, Julie, it's one helluva lot better — one HELLUV A lot better — to be born dirt-poor. Course then you get to stay that way the rest of your life.1977, Curt Johnson, The Morning Light, page 214:
“That's the helluv it — beggin' yer pardon, miss...”1997, Kat Martin, Innocence Undone, page 297:
“Helluv it is,” he grumbled. “I was thinking of marrying her myself. Wrote her a letter, but it didn't get posted in time.”1997, Kat Martin, Innocence Undone, page 173: