What is a stem cell definition?

A starter cell: A stem cell is a cell that produces more specialized cells. If you imagine all of the possible finished cells as leaves on a tree, with in between cells as the branches, the stem would be the trunk.

See below: Stem cells are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into diverse specialized cell types and can self-renew to produce more stem cells. In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.