'cholecystitis' originates from Neo-Latin/modern medical coinage, specifically from the Greek elements 'chole' meaning 'bile', 'kystis' meaning 'bladder' or 'sac', and the suffix '-itis' meaning 'inflammation'.

'cholecystitis' was formed in medical terminology (19th century) by combining Greek roots into Neo-Latin 'cholecyst-' + '-itis', and entered English via medical Latin and medical usage.

Initially it referred broadly to inflammation of a bile-containing bladder or cyst; over time it became the specific term for inflammation of the gallbladder.