to discipline: to correct and train someone for their good, by words or by hardship or by blows
This verb covers the whole work of forming a person through correction. At one end it is teaching and warning with words, the way a parent admonishes a child or a teacher trains a pupil. In the middle it is the harder correction that comes through trouble and pain, especially the way God lets suffering fall on his people to turn them back. At the strongest end it is bodily punishment: a beating with a rod or a whip.
What holds these together is purpose. Unlike a word that means simply to punish or to strike, this verb almost always carries the aim of reform. The point is not to vent anger or destroy, but to teach a lesson that changes the person. That is why the Bible can call the one who is disciplined by God blessed, and why a parent is told to discipline a child out of love.
The related noun built on this root is the common word for instruction, training, and moral teaching, especially in Proverbs. So the verb sits at the meeting point of teaching and correcting: to discipline is to teach the hard way, and to teach is the gentlest form of discipline.
In its passive and reflexive forms the verb means to be corrected, to learn the lesson, or to take warning, that is, to let oneself be set straight.