Green’s Dictionary of Slang

1. intoxicated by a drug, esp. a hallucinogen.

1966		in Mojo Navigator 22 Nov. n.p.: Every time Joe McDonald gets spaced he sings old folk songs.
1968		T. Wolfe Electric Kool-Aid Acid Test (1969) 193: Every freak in California now showing up [...] looking to get spaced out on LSD.
1971		J. Mandelkau Buttons 68: I remember being really spaced out.
1973		Harper’s Mag. June 32: Taking psychedelics in vast, empty spaces. They were spaced.
1988		J. Healy Grass Arena (1990) 103: Both spaced out, we must have been on the third machine when the law came running down the platform.
1989		H. Rawson Dict. of Invective (1991) 369: The use of spaced and spacey to describe people who are out of contact with reality because they are high on drugs.
1991		B. Stewart Broken Arse I vi: We’re better doing this than being spaced out on downers.
2000		M. Manning Get Your Cock Out 9: The kids dug The Leather Cowboys and their spaced-out brand of space age boogie.
2007		R. Milward Apples (2023) 143: I was more spaced out [on MDMA] than supercharged.
2019		A. Parks February’s Son 171: [S]uddenly sounding more like a Carntyne dealer than a spaced-out hippie.

2. generally disorientated, without the use of drugs.

1969		Gandalf’s Garden 6 n.d. 11: spaced: a mental state in which one is unable to collect one’s thoughts, giving the impression of vagueness and abstractedness. Usually the aftermath of a drug experience, or the product of a mind overburdened with problems and pressures which negate cohesive thinking.
1977		C. McFadden Serial 47: She just sort of stood there, feeling totally spaced.
1978		T.H. White In Search of Hist. 355: A few weeks later, following incomprehensible letters saying I had been ‘spaced out’.
1985		R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 29: A team of spaced-out New Zealanders held him up.
1987		T. Wolfe Bonfire of the Vanities 454: They just busted that social club up on 167th. There’s twelve fucking spaced-out carambas in line waiting to get into Central Booking.
1991		C. Hiaasen Native Tongue 282: The poor guy was completely spaced. Thought he was Rommel.
1998		R.G. Barrett Mud Crab Boogie (2013) [ebook] ‘We might be just a couple of spaced-out trekkies [...] [b]ut we’re light years in front of you’.
1999		Guardian Weekend 14 Aug. 3: They were long ago killed by their spaced-out husbands or dumped for younger models.
2000		Indep. Rev. 14 Feb. 20: A spaced-out fan arrived on the doorstep.
2016		Guardian G2 8 Aug. 🌐 Jaden Smith, whose somewhat spaced-out air is put to good use in his role as [...] graffiti-obsessed Dizzee.

3. (US teen) drunk.

1981

Detroit Free Press (MI) 6 July 17/1: spaced out — drunk.