Hella. Originated from the streets of San Francisco in the Hunters Point neighborhood. It is commonly used in place of "really" or "very" when describing something.
The Fillmore is hella better than the Mission.

Thank God LA is hella far away.
by TeknoTurd May 28, 2004
The farmers from Northern California who settled here a long time ago (probably before the 1950's) were patient and slow people and took everything with ease. When they communicated to explain "VERY" they would say "hell of a" instead of "very" or "a lot". Then the city folks who migrated in later to the Bay Area took the Northern California farmers saying and shortened it to "Hella" instead of "Hell of a."
So in the end the word "hella" comes from the Bay Area city folks. Short and sweet.
She/he was hella sweet.
It was hella cool.
The ride was hella fresh.

by Bay area gurl January 28, 2009
very, totally; lots of

N.B. Generally used in Northern California.
1. That party was hella sketch. What with all those skanky-ass girls.
2. There was HELLA weed tho!
by NorCAL all the way March 1, 2003
"Hella" is an all-purpose word. It has its roots deep in the soul (I meant to type soil, but soul works here too, haha) of Northern California. It means something along the lines of "very" or "really," but it's much more than that. It's not just a word, but a statement of cultural identification, of a long-standing bond of trust and respect for fellow Northern Californians, and of a mutual understanding between you and the rest of the world that you are from (or, in the case of anyone who has lived with kids from NorCal, that you are an honorary resident) NorCal. As the subtle innuendoes of the word can only be understood by absorption, one must experience and be engulfed by it (as Northern Californians are from birth) to truly understand when its usage is appropriate. Hella is a word. It's a symbol. It's a way of life. Hella.
Correct:

This is hella whack.
I just ate hella brownies.
I'm hella going to the library this weekend.

Incorrect:
I'm going hella to the library
by NorCal, May 22, 2008
An intensifier, with a grammatical function and usage similar to "very" or "really".

It's a contraction of "hell of", and may have originated in Alameda County, California. It was definitely in common use in Berkeley public schools as far back as 1979.
"That party was hella rad." (ca. 1981)
by Chris December 24, 2004
My own extensive research has found that the term 'hella' or 'hellof' did not originate in San Francisco, but rather Oakland, as the first anyone remembers hearing it was Oaklnd in 1976, then later. in the early 80s in San Francisco.
I tripped on my shoe laces hella times today.
by steve September 24, 2004
A word originating in the San Francisco Bay Area and used by Northern Californians. It is often a symbol of one's Bay Area words. It is a word of convenience, since it can be used in many parts of speech. As an adjective, it means "a lot of, many, various." As an adverb, it means "really, actually, very, in a high degree." It may also mean "I agree."

It may be useful to note that the expression "hella days" usually denotes a length of time much longer than several days.
Adjective:
"I just saw hella people running out of that building, is there a fire?"

Adverb:
"I ate too much. I'm hella full right now."

Affirmation:
"That was the best night of my life."
"Hella! Me too."
by srhlwrc February 16, 2009