Where did the word groovy come from? The answer takes us back to the early days of electronic sound production, to the Jazz Age, and to the outta sight world of the ’60s.
First, take a look at the word itself: groovy refers to something that’s in the groove. What groove?
The grooves on a record.
The phonograph, invented in 1887 by Thomas Edison, changed the way the world listened to music. Audio could now be recorded and played back in another place and another time. The phonograph recorded the vibrations of sound waves by etching corresponding grooves on a wax cylinder. To play the recorded sound, a stylus traced over the grooves, causing the same vibrations in the air. Later on, flat vinyl discs were used instead of wax cylinders to record the grooves, and the term gramophone was coined for the device.

Image by Tbraunstein, CC BY-SA 3.0 via Wikimedia Commons.
The Jazz Age of the 1930s brought a swinging, syncopated sound to America—a sound that, when performed well, was described as being groovy. Jazz musicians were in the groove if they were perfectly in sync with the music, playing with swing and soul. The analogy was that the musician followed the music precisely just as a phonograph stylus follows the grooves on a record. It was a synergy of contradiction, of being in sync but with a colorful, dissonant, improvised swing.

Groovy was generalized slightly to take on the meaning of “first-rate, excellent” by 1937. By the 1960s, semantic drift led to the popular use of groovy as slang for “really cool,” “wonderful,” “fun,” or “good-looking.” The term hit peak popularity during the ’60s and ’70s. Though the term largely fell out of use by the ’80s, groovy is still used as a reference to the iconic days of tie-dye and disco.
Or if you’re Shaggy from Scooby Doo, it’s a term used to describe the alien girl of your dreams.
Sources
Demain, Bill. “Jive Talkin’: The Origins of Cool Dudes, Groovy Chicks and Hip Cats.” January 19, 2012. MentalFloss. https://www.mentalfloss.com/article/29777/jive-talkin%E2%80%99-origins-cool-dudes-groovy-chicks-and-hip-cats.
groovy (adj.) Etymology Online Dictionary. Accessed October 9, 2020. https://www.etymonline.com/word/groovy.
Phonograph, Wikipedia. Accessed October 9, 2020. https://en.wikipedia.org/wiki/Phonograph.