noun
pulmonology; respiratory medicine
Medical specialty dealing with the respiratory system; used in academic and clinical contexts.
彼は呼吸器学の専門医です。
He is a specialist in pulmonology.
呼吸器科 refers to the department of respiratory medicine in a hospital, while 呼吸器学 is the academic discipline itself.
Compound of 呼吸器 (respiratory organs) and 学 (study, -ology).