IPA: /rɪˈdʒɛmənˌtəl/
KK: /rɪˈdʒɛmənˌtəl/
Relating to a military unit or behaving in a strict and disciplined manner, similar to how soldiers in a regiment would act.
The regimental rules were enforced to maintain order during the training exercises.
Regimental → It is formed from "regiment" (from Old French *regiment*, meaning a system of government or rule) and "-al" (meaning pertaining to). The word "regimental" refers to something that pertains to a regiment, which is a military unit.
Think of a regiment as a group that is organized under a system of rule, and the suffix '-al' indicates that something is related to that group.