Refers to a state of extreme, irrational suspicion or delusional thinking, often used in psychological or colloquial contexts.
He couldn't trust anyone and became paranoid.
被害妄想 refers specifically to persecutory delusions, a subtype of paranoia, whereas 妄想狂 can encompass broader paranoid conditions.
megalomania
Compound of 妄想 (delusion) and 狂 (madness, insanity). The exact historical derivation is uncertain, but the term likely emerged in modern medical or psychological contexts.