shell shocked

Short definition from Wiktionary

Adjective

1. 1
   Alternative form of shell-shocked.
2. 2
   Stunned or mentally unbalanced by prolonged stress such as experienced in combat or under fire (shell-fire); suffering from post-traumatic stress disorder.
3. 3
   Confused as a result of a traumatic experience.

Verb

1. 1
   simple past and past participle of shell shock