Witnessing that fire in childhood was a traumatic event that left him with lasting scars.

traumatic 是形容词，来自名词 trauma（创伤、精神创伤）。trauma 源自希腊语，本义是"伤口"，后来引申为"心理创伤"。traumatic 表示"造成创伤的、令人痛苦的"，形容事件给人带来长期的心理伤害。