Green’s Dictionary of Slang

spacey adj.

also spacy
[spaced (out) adj.]
[1960s+]

1. intoxicated by a drug, exhibiting signs of disorientation or being out of touch with reality, following the ingestion of a hallucinogen or of cannabis.

2. exhibiting characteristics reminiscent of those experienced when taking a hallucinogen.

3. (drugs) of an experience or event, generally disorientating, with or without drugs.

4. edgy, nervous.