Which combining form is used to denote blood?

• A. Dermat/o
• B. Enter/o
• C. Irid/o
• D. Hem/o, hemat/o

Answer: (D)

Blood is shown in medical terms by the combining forms hem/o- and hemat/o-. These roots mean blood and are used to form words about blood, with the linking vowel -o- helping connect to suffixes such as -logy (hematology) or -globin (hemoglobin). The other roots point to different body parts: dermat/o- means skin (dermatology), enter/o- means intestine (enteritis, enteropathy), and irid/o- means the iris of the eye (iriditis). So for terms involving blood, hem/o- or hemat/o- are the correct building blocks.