the.com/pneumonitis

means Inflammation of the lung tissue itself, which may or may not be caused by an infection — think allergens, radiation, toxins, or autoimmune trouble.

from Built from Greek pneumon, 'lung' (related to pneuma, 'breath' or 'wind'), plus the medical suffix -itis, meaning 'inflammation.' The -itis tag is the same one riding along in arthritis and tonsillitis — a 19th-century convention for naming diseases by the body part that's suffering.