oneirism vs castle in Spain

oneirism and castle in Spain both are nouns.

Word	Noun	Adjective	Verb	Adverb
oneirism	Yes	No	No	No
castle in Spain	Yes	No	No	No

As nouns, oneirism and castle in Spain are synonyms defined as:

Other synonyms of oneirism include air castle, castle in the air, daydream, daydreaming, reverie, revery.

oneirism (noun)	castle in Spain (noun)
absentminded dreaming while awake	absentminded dreaming while awake