What term is used to describe unlimited cell division?

The term that describes unlimited cell division is best referred to as immortality. Immortality in cellular biology denotes the ability of cells to divide an infinite number of times without undergoing senescence, which is the process where cells lose their ability to proliferate after a certain number of divisions. This characteristic is especially relevant when discussing cancer cells, which often exhibit immortality through various mechanisms, such as the activation of telomerase.

In contrast, metaplasia refers to the abnormal transformation of one type of tissue into another, often as a response to stress or injury, and does not imply an unlimited capacity to divide. Contact inhibition is a phenomenon where cells stop dividing when they come into contact with each other, which is often lost in cancer cells, allowing for continuous growth. Neoplasia refers to the abnormal proliferation of cells, which can lead to tumor formation, but it does not specifically denote the characteristic of unlimited division that immortality captures. Thus, immortality is the most accurate term to express the concept of unlimited cell division.