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Webster 1828 Edition

Adj.

unhelth'ful.

Not healthful; injurious to health; insalubrious; unwholesome; noxious; as an unhealthful climate or air.

Abounding with sickness or disease; sickly; as an unhealthful season.

unhealthful ‎(comparative more unhealthful, superlative most unhealthful)

Not healthy; detrimental to health.
An unhealthful diet and lack of exercise are common causes for heart disease.

not healthy