Regimental means belonging to a regiment, or rigidly organised. Regimental colours, regimental tie, regimental discipline.
The regiment is the unit soldiers identify with, and regimental traditions, museums and marches all attach to it rather than to the army as a whole. The second sense — rigidly organised — is a mild criticism when applied to a household or an office. Note regiment, regimented; and the striped regimental tie.
1adjectiveregimentalBelonging to a regiment.
“The regimental band played as the soldiers marched through the town.”
2adjectiverigidlyRigidly organised.
“Their mornings run with regimental precision: up at six, breakfast at seven, out by half past.”
regimental is a quality of military organisation.
Proto-Indo-European
*h₃reǵ-
Latin
regimentum — direction for government; course of medical treatment
Middle French
regement
English
regiment
English, today
regimental
From regiment + -al. regiment comes from Middle French regement, régiment, and its source, Latin regimentum (“direction for government; course of medical treatment”), from Latin regō (“rule”).
Etymology from Wiktionary, CC BY-SA