Green’s Dictionary of Slang

a general excl. of approval, pleasure.

1967		J. Rechy Numbers (1968) 129: ‘Groovy,’ the guy in the sweatshirt calls out.
1973		E. Bunker No Beast So Fierce 176: ‘We can blow a couple of joints, drive around, and see if we really like each other.’ ‘Groovy.’.
1983		Eble Campus Sl. Mar. 3: groovy cool – fantastic.
1996		(con. 1970) G. Moxley Danti-Dan in McGuinness Dazzling Dark (1996) I ix: Groovy baby.