This adjective that describes something cool, hip, and happening is synonymous with the ‘60s, but it didn’t originate there. Groovy actually dates to the 1930s, when musicians were said to be in a focused state of mind while playing, or when something was thought to be excellent in general. It’s since taken on a kind of postmodern meaning and is used today to derisively and ironically refer to the outdated culture of the ‘60s.

Source: Mental Floss