Real Dictionary

vitalism in American English
the doctrine that the life in living organisms is caused and sustained by a vital force that is distinct from all physical and chemical forces and that life is, in part, self-determining and self-evolving
noun: the doctrine that phenomena are only partly controlled by mechanical forces, and are in some measure self-determining

vitalism in British English
noun: the philosophical doctrine that the phenomena of life cannot be explained in purely mechanical terms because there is something immaterial which distinguishes living from inanimate matter