adjective, health·i·er, health·i·est.

1.  Possessing or enjoying good health or a sound and vigorous mentality: a healthy body; a healthy mind.
2.  Pertaining to or characteristic of good health, or a sound and vigorous mind: a healthy appearance; healthy attitudes.
3.  Conducive to good health; healthful: healthy recreations.
4.  Prosperous or sound: a healthy business.
5.  Informal. fairly large: I bought a healthy number of books.