From Latin 'disciplina' (instruction), from 'discere' (to learn), from PIE *dek- (to accept). Sibling of 'disciple.'
The practice of training people to obey rules or a code of behavior; a branch of knowledge or teaching.
From Old French descepline (discipline, learning, training), from Latin disciplīna (instruction, teaching, a branch of learning, trained conduct), from discipulus (pupil, learner, one who takes in learning), from discere (to learn), from PIE *dk̑-ske- (a suffix-extended form of *dek̑-, to take, to accept, to perceive as fitting). The PIE root *dek̑- also underlies Latin decus (honor, ornament), decere (to be fitting), doctor, and docile — all words about taking in what is right or fitting. Discipline and disciple are sibling words: discipline names
The words 'discipline' and 'disciple' are siblings — both from Latin 'discere' (to learn). A disciple is a learner; a discipline is what is learned (or the training that produces learning). The punitive sense of 'discipline' (punishment, correction) developed because the medieval Church practiced 'disciplina' as physical mortification — scourging as a form of spiritual learning. The academic sense ('a discipline of study') preserves the original meaning: a