If a patient has a sinus infection, which root word best describes this condition?

The root word that best describes a sinus infection is "sinus/o." This term specifically refers to the sinus cavities within the skull, which can become infected and inflamed during a sinus infection, also known as sinusitis. The use of "sinus/o" in medical terminology allows healthcare professionals to clearly identify conditions related to the sinuses when discussing symptoms, treatment, or anatomy.

The other root words do not relate to sinus infections: "somn/o" pertains to sleep, "spermat/o" relates to sperm or male reproductive cells, and "sphygm/o" refers to pulse. Thus, these terms would not be appropriate choices for describing a condition involving sinus infection. The targeted focus on the sinus cavities makes "sinus/o" the most accurate and relevant root word for this condition.