from the GNU version of the Collaborative International Dictionary of English
- adj. in the British army, a school for the instruction of the private soldiers of a regiment, and their children, in the rudimentary branches of education.
Sorry, no etymologies found.
I have spoken twice to the commander, telling him that a regimental school for the youngsters would not be amiss at all, but he balks at the idea of mixing officers 'children with those of enlisted men, let alone the townsfolk.