a person who appears to be in his or her own world or out of touch with reality.
a person who behaves oddly or seems stupefied or remote because of the influence of drugs; druggie.
Words nearby space cadet
Origin of space cadet
1950–55, for sense “spaceman trainee”
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for space cadet
slang a person who is eccentric or out of touch with reality, as if affected by drugs
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012