substantial form

In philosophy, substantial form is a core concept within hylomorphism, a doctrine primarily associated with Aristotle. Hylomorphism posits that every natural object is a composite of two intrinsic principles: potentiality, known as primary matter, and actuality, known as substantial form.312

Substantial form is the principle that gives an individual substance its specific or generic character, defining what it is. Matter, on the other hand, is the potential principle, the underlying stuff from which things develop. Form actualizes this potential, determining what the matter becomes. For example, bricks and mortar are the matter that, when given the form of a house, become a house. This concept was central to Aristotle's philosophy of nature and was later adapted by philosophers like Thomas Aquinas.4351