军纪

Almost always paired with strong adjectives: 严明 (yánmíng, 'strict and clear'), 严格 (yángé, 'rigorous'), or — negatively — 松弛 (sōngchí, 'lax') and 涣散 (huànsàn, 'disorganized'). 整顿军纪 (zhěngdùn jūnjì, 'to tighten military discipline') is a stock phrase in news about reforms and crackdowns.

memory

军 (jūn) 'army' + 纪 (jì) 'rules / chronicle' (the same 纪 as in 纪律 jìlǜ 'discipline'). Compose any group with 纪 and you get 'rules of that group': 校纪 school discipline, 党纪 party discipline.