cosmic, adj. — Green’s Dictionary of Slang

cosmic adj.

[SE cosmic, i.e. the contemporary interest in psychedelic drugs]

excellent, first-rate, perfect, overwhelming.

1967		W. Murray Sweet Ride 37: Cosmic let downs, chickie. Absolutely cosmic betrayals. Lousy breaks.
1977		C. McFadden Serial 42: It was cosmic of Kate to flash on it like that.
1981		J. Sullivan ‘A Slow Bus to Chingford’ Only Fools and Horses [TV script] No, that is cosmic Janice. No really – no that is cosmic that.
1999		Guardian 31 July 21: Bailey’s Beads shining through the valleys of the moon! Cosmic!
2001		Guardian Rev. 10 Mar. 2: Hey! Wow! Cosmic!