noun
Academic field covering public health, hygiene, and preventive medicine.
彼女は大学で保健学を専攻している。
She is majoring in health sciences at university.
公衆衛生 is public health as a field or practice; 保健学 is the academic discipline.
Compound of 保健 (health preservation) and 学 (study). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.