[speyst-out or speyst]
dazed or stupefied because of the influence of narcotic drugs.
dreamily or eerily out of touch with reality or seemingly so; spacey.
Origin of spaced-out
1965–70, Americanism; on the pattern of phrasal verbs with out marking perfectivity; space apparently by association with “outer space” as, metaphorically, a place outside normal consciousness
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019