Proliferation in medical terms, refers to a trophoblastic tissue. In biology, cell proliferation refers to the development of the cells and the cell division process. In reference to the cell development, proliferation concerns itself with the cytoplasmic and organelle volume, and their increase. Furthermore, it also refers to an increase in the genetic matter after the S phase.
However, one must not confuse it with the cell division. In the context of cell division, proliferation is referred to as the division of cell into two daughter cell from a mother cell. Hence, this term has a different meaning in different biological contexts.