Final answer:
Poikilocytosis is the correct term that refers to variation in red blood cell (RBC) shape, often seen in conditions like sickle cell anemia.
Step-by-step explanation:
The term Poikilocytosis refers to variation in RBC shape. This condition is often observed in various diseases, including sickle cell anemia, where abnormal hemoglobin S production leads to erythrocytes assuming a sickle or crescent shape.
These irregularly shaped cells can become stuck in capillaries, causing a range of complications. Such variations in cell morphology are critical for diagnosis and understanding the impacts on oxygen delivery.