Final answer:
The term that means a deep furrow or cleft is fissure. In cell biology, a fissure refers to the cleavage furrow formed during cytokinesis.
Step-by-step explanation:
The term that means a deep furrow or cleft is fissure. In the context of cell biology, a fissure can refer to the cleavage furrow formed during cytokinesis in animal cells. This furrow is a contractile band made up of actin filaments that forms around the midline of the cell and deepens as the actin ring contracts, eventually leading to cell division.