Which combining form means dark blue?

• A. Somat/o
• B. Cyan/o
• C. Oste/o
• D. Myel/o

Answer: (B)

Dark blue in medical terms comes from combining forms that name a color. The combining form cyan/o denotes blue and is used in terms like cyanosis, which describes a bluish or dark bluish skin color due to reduced oxygen. The other options refer to body parts—somat/o means body, oste/o means bone, and myel/o means the spinal cord or bone marrow—so they describe locations rather than color. Therefore, cyan/o is the correct combining form for dark blue.