1.
trauma, psychological trauma
A deeply distressing experience that causes lasting psychological harm. In casual usage, also used loosely for any bad experience that leaves a lasting negative impression.
Etymology
From German/English "trauma." Entered Japanese primarily through psychology.
Usage
In formal or medical contexts, トラウマ retains its clinical meaning of serious psychological injury. In casual speech, it is used more loosely — 数学がトラウマ ("math is my trauma") simply means one has a strong aversion to math from a bad experience.
Common patterns
Commonly used with になる: トラウマになる (to become a trauma, to be traumatized by something).