leucopenia

/ˌluːkəˈpiːniə/
noun
  1. A medical condition in which there are fewer white blood cells than normal, often making it harder for the body to fight infections.
    • Doctors monitored her leucopenia closely to prevent any serious infections.
    • The patient's leucopenia was discovered during a routine blood test.
    • Chemotherapy can sometimes cause leucopenia as a side effect.