The Collaborative International Dictionary
Traducianism \Tra*du"cian*ism\, n. (Theol.) The doctrine that human souls are produced by the act of generation; -- opposed to creationism, and infusionism.
Wiktionary
n. (cx religion English) The doctrine that the soul or spirit is inherited from one or both parents.
Wikipedia
In Christian theology, traducianism is a doctrine about the origin of the soul (or synonymously, " spirit"), holding that this immaterial aspect is transmitted through natural generation along with the body, the material aspect of human beings. That is, an individual's soul is derived from the souls of the individual's parents. This implies that only the soul of Adam was created directly by God (with Eve's substance, material and immaterial, being taken from out of Adam), in contrast with the idea of creationism of soul (not to be confused with creationism as a belief about the origin of the material universe), which holds that all souls are created directly by God (with Eve's substance, material and immaterial, being taken from out of Adam).