A recent Twitter exchange between William Gibson and Simon Max Hill:
— simonmaxhill (@simonmaxhill) February 3, 2014
Wouldn't it be wonderful if a term from high philosophy had really penetrated the street slang of Oakland? Alas, it looks like a case of false cognates.
First, haecceity (pronounced /hɛkˈsi:ɪti/), as defined by the Stanford Encyclopedia of Philosophy:
First proposed by John Duns Scotus (1266–1308), a haecceity is a non-qualitative property responsible for individuation. As understood by Scotus, a haecceity is not a bare particular in the sense of something underlying qualities. It is, rather, a non-qualitative property of a substance or thing: it is a “thisness” (a haecceitas, from the Latin haec, meaning “this”) as opposed to a “whatness” (a quidditas, from the Latin quid, meaning “what”).
While its companion quiddity did enter more common usage (as in "quirks and quiddities," where quiddity means 'quibble'), I don't think haecceity has made it very far out of philosophical circles.
Now for the Oakland slang: it's pronounced something like /ˈhɛksɪti/ (with intervocalic /t/ typically reduced to an alveolar flap [ɾ]) and can be spelled in a variety of ways, including hecksitty, hecksity, and hecksiddy. Berkeley-bred Jorma Taccone of the sketch comedy troupe The Lonely Island spells it as hecksadee:
Jimmy Fallon was hecksadee fun just now!! Check us out Late Night tonight if you like Fake Rap and also The Roots being awesome!
— Jorma Taccone (@jormataccone) July 25, 2013
And Simon Max Hill himself spelled it as hexiddy when he entered the word into Urban Dictionary in 2007:
This is an intensifier, commonly referring to a great number of a thing or a great intensity of an experience.
This is an alternate for the word "hella", the Northern California slang especially prevalent in the Bay Area. Scholars, drunks and amateur librarians suggest that the word originated in stricter households where the word "hella" was considered inappropriate due to the word "hell" being involved.
"You stabbed him twice with a pencil and ganked his Now'n'Laters? That's hexiddy raw, cuz."
by simon max hill December 05, 2007
As Hill suggests, the term owes its roots to the Bay Area slang intensifier hella and its more polite cousin hecka. Hella has been well studied — see, for instance, "Hella Nor Cal or Totally So Cal? The Perceptual Dialectology of California" (Mary Bucholz et al., Journal of English Linguistics), "Northern Californian English: Hella Different?" (Asya Pereltsvaig, GeoCurrents), and "Hella Gets Huge" (Mark Peters, Good). Recently, hella has also been examined dialectologically on Twitter: see "A Latent Variable Model for Geographic Lexical Variation" (Jacob Eisenstein et al., EMNLP 2010) and "Examining Large-Scale Regional Variation Through Online Geotagged Corpora" (Brice Russ, ADS 2012).
As for hecka, Grant Barrett traced it back to 1985 on his Double-Tongued Dictionary site, though that example ("We had a hecka season") seems to be a shortened form of heckuva. The more typical adverbial intensifier ('very') appears as early as 1987 in the Prince song "U Got The Look" (featuring Sheena Easton): "Your face is jammin' / Your body's hecka slammin'." Pamela Munro's 1989 book Slang U. shows it was already in common use among UCLA students by then (example: "You're still studying at this hour? It's hecka late").
Used like hecka(see Hecka) but for a much stronger application, or when trying to really get your point across. Traced to Tsubouchi, and the East Bay.
1st person "Did you see that flipped over car on the freeway? That was hecka crazy!"
2nd person "No,that shit was on fire too, it was HECKSA crazy!!"
by guru_ January 10, 2006
And from hecksa we can get to hecksit(t)y by suffixing it with -it(t)y. That suffix shows up occasionally in such colloquialisms as uppity and biggity. For some it may suggest the -ity/-ety found in such reduplicated forms as flippity-flop or blankety-blank. Most likely it's a playful elaboration akin to hiphop's "[IZ]-infixation," the kind of elaboration that allowed Sean Combs to transmute his "Puff Daddy" nickname to "P. Diddy." (Compare the -iggity ending that allows no doubt to become no diggity, or wack to become the reduplicated wiggity-wack. I also hear an echo of saditty, old African-American slang for 'snobbish, conceited.') However it was formed, there's no apparent connection to the nominalizing suffix -ity indicating a state or condition, which we find at the end of haecceity. And that's just about enough thisness for now.
(Hat tip, Jeff Martin.)