Select the most appropriate one-word substitution for the given group of words.

A mental condition in which person thinks he's ill even if he's not 

Hypochondria

The most appropriate one-word substitution for "a mental condition in which a person thinks he's ill even if he's not" is hypochondria.

• Psychopath is a person with a personality disorder characterized by antisocial behavior, lack of empathy, and a disregard for the rights of others.
• Hypochondria is a mental illness characterized by an excessive and unrealistic worry about one's health.
• Imbecile is a now-obsolete term for a person with a mild intellectual disability.
• Panache is a flamboyant or showy style or manner.