depression：(心情)抑郁；(经济)萧条  

词根词缀：de-向下 + -press-压 + -ion名词词尾

• irregular
• irregularity
• irrelevance
• irrelevant
• irreligious
• irremediable
• irreparable
• irreplaceable
• irrepressible
• irreproachable
• irresistible
• irresolute
• irrespective
• irrespective of
• irresponsible
• irretrievable
• irreverent
• irreversible
• irrevocable
• irrigate
• irritable
• irritant
• irritate
• irritation
• irritative