In its most general sense, discipline refers to systematic instruction given to a disciple. This sense also preserves the origin of the word, which is Latin disciplina "instruction", from the root discere "to learn," and from which discipulus "disciple, pupil" also derives.

To discipline thus means to instruct a person or animal to follow a particular code of conduct, or to adhere to a certain " order." Consequently, "in the field of child development, discipline refers to methods of modeling character and of teaching self-control and acceptable behavior." So for example, to discipline a child to wash her/his hands before meals. Here, 'washing hands before meals' is a particular pattern of behaviour, and the child is being disciplined to adopt that pattern. 'To disciple' also gives rise to the word disciplinarian, which denotes a person who enforces order.

Usually however, the phrase 'to discipline' carries a negative connotation. This is because enforcement of order - that is, ensuring instructions are carried out - is often regulated through punishment.^cf.

To be disciplined is then, subject to context, either a virtue (the ability to follow instructions well) or a euphemism for punishment (which may also be referred to as disciplinary procedure). As a concrete noun, the discipline refers to an instrument of punishment, for example in mortification of the flesh (see also: flagellation). Such an instrument may also be applied to oneself, for example in penitence for not being sufficiently self-disciplined.

Self-discipline refers to the training that one gives one's self to accomplish a certain task or to adopt a particular pattern of behaviour, even though one would really rather be doing something else. For example, denying oneself of an extravagant pleasure in order to accomplish a more demanding charitable deed. Thus, self-discipline is the assertion of willpower over more base desires, and is usually understood to be a synonym of 'self control'. Self-discipline is to some extent a substitute for motivation, when one uses reason to determine a best course of action that opposes one's desires. Virtuous behaviour is when one's motivations are aligned with one's reasoned aims: to do what you know is best and to do it genuinely gladly. Continent behaviour, on the other hand, is when one does what one knows is best, but must do it by opposing one's motivations., Fowers BJ. 2008, From Continence to Virtue: Recovering Goodness, Character Unity, and Character Types for Positive Psychology. Theory & Psychology, Vol. 18, No. 5, 629-653 Moving from continent to virtuous behaviour requires training and some self dissicipline.

Self discipline can also be linked to 'school discipline', 'church discipline' and even 'academic discipline'.

School discipline refers to regulation of children and the maintenance of order ("rules") in schools. These rules may, for example, define the expected standards of clothing, timekeeping, social behaviour and work ethic. The term may also be applied to the punishment that is the consequence of transgression of the code of behavior. For this reason the usage of school discipline sometimes means the administration of punishment, rather than behaving within the school rules.