Thayer's Greek Lexicon

 1. the whole training and education of children (which relates
to the cultivation of mind and morals, and employs for this
purpose now commands and admonitions, now reproof and
punishment) It also includes the training and care of the body
2. whatever in adults also cultivates the soul, esp. by
correcting mistakes and curbing passions.
  1) instruction which aims at increasing virtue
  2) chastisement, chastening, (of the evils with which God
visits men for their amendment)