The Collaborative International Dictionary of English v.0.48:

Healthy \Health"y\ (-[y^]), a. [Compar. Healthier
   (-[i^]*[~e]r); superl. Healthiest.]
   1. Being in a state of health; enjoying health; hale; sound;
      free from disease; as, a healthy child; a healthy plant.
      [1913 Webster]

            His mind was now in a firm and healthy state.
                                                  --Macaulay.
      [1913 Webster]

   2. Evincing health; as, a healthy pulse; a healthy
      complexion.
      [1913 Webster]

   3. Conducive to health; wholesome; salubrious; salutary; as,
      a healthy exercise; a healthy climate.

   Syn: Vigorous; sound; hale; salubrious; healthful; wholesome;
        salutary.
        [1913 Webster]

WordNet (r) 3.0 (2006):

healthier
    adj 1: improved in health or physical condition [syn: fitter,
           healthier]