Which combining form means heat or fire?

• A. Neur/o
• B. Diaphor/o
• C. Pyr/o
• D. Physic/o

Answer: (C)

Heat or fire is expressed by the combining form pyr/o. From Greek pyr- meaning fire, it appears in medical terms like pyrogen (a substance that causes fever) and pyrosis (a burning sensation, as in heartburn). The other options point to different concepts: neur/o is nerve, diaphor/o relates to sweat, and physic/o refers to nature or the physical world, none of which convey heat or fire. So pyr/o is the form that means heat or fire.