To understand how this word can have such divergent connotations, it helps to plumb its complicated history. Spaz emerged in American slang in the 1950s, a clipping of spastic, with its pronunciation influenced by the related words spasm and spasmodic. Spastic had been used in medical circles since the 18th century, first as a word to describe a muscular spasm and then in the name of conditions marked by involuntary spasms, as in spastic paralysis or spastic diplegia. By the early 20th century, spastic could be used in medical literature as an adjective meaning “affected with spastic paralysis,” as in “spastic children,” or as a noun for a person with that type of paralysis.
Spastic itself underwent what linguists call “pejoration” as it became a playground taunt, often to ridicule someone’s uncoordinated behavior. As with spaz, the connotations of spastic have been more negative in British English than across the Atlantic. A U.K. charity for people with cerebral palsy was founded in 1952 as the Spastic Society but eventually changed its name to Scope to avoid the insulting use of spastic. (Slang dictionaries record that scope or scoper then became a new insult for “an inept, clumsy or stupid individual” on British playgrounds.) In 2014, Weird Al Yankovic found himself on the receiving end of British criticism similar to what Lizzo and Beyoncé experienced, when he included spastic in his song “Word Crimes.” He tweeted an apology: “If you thought I didn’t know that ‘spastic’ is considered a highly offensive slur by some people… you’re right, I didn’t. Deeply sorry.”
As for spaz, also spelled spazz or spas, the earliest documented uses in American English show that it was related to wild or uncontrolled movements without necessarily targeting people with physical disabilities. In the fall of 1956, Yale University football coach Jordan Oliver was quoted by the Hartford Courant after a game against Cornell: “We were a little spasmodic, but when we didn’t ‘spaz’ we looked very good.” A year later, the syndicated business columnist J.A. Livingston used the verb in a more general way for unexpected movements in the stock market, writing that “jewelers, furriers, and furniture dealers go through… merchandising tortures whenever Wall Street spazzes.”
Meanwhile, spaz was entering collegiate slang. Joe Fineman, a 1958 graduate of Caltech, shared a journal entry that he wrote in 1956 on the language of his fellow students:
SPAZ, n.R (shortened from spastic) 1. Obsolete. A person lacking in the common social skills & virtues. See TWITCH. 2.
To surprise a person in a way that causes him to take some time to react. v.R