healthier
Health is not an adjective and therefore does not have comparative and superlative forms.Healthy, however, is an adjective, with the comparative form of healthier and the superlative form of healthiest.
healthier
well (healthy) comparative is better and superlative is the best
Healthier is comparative of healthy.
The comparative form of busy is busier.
The comparative form of dreamy is dreamier
The comparative form of friendly is friendlier.
healthier
healthier
comparative form is cleaner superlative form is cleanest
healthier, more healthy
The comparative form of "central" is "more central."