Which combining form signifies white or colorless, related to leukocytes?

• A. Leuk/o
• B. Xanth/o
• C. Calc/i
• D. Chondr/o

Answer: (A)

Leuk/o is the combining form that signifies whiteness or colorlessness and is directly tied to leukocytes, the white blood cells. The term leukocyte itself comes from the Greek leukos, meaning white, reflecting the white appearance of these cells on many stains. This same root appears in related terms like leukemia (a disease of white blood cells) and leukocytosis (an increase in white blood cells). The other options point to different meanings: xanth/o means yellow, calc/i relates to calcium or stones, and chondr/o refers to cartilage.