唯物论（英语：materialism），哲学理论，肯定世界的基本组成为物质，物质形式与过程是我们认识世界的主要途径，持着「只有事实上的物质才是真实存在的实体」的这一种观点，并且被认为是物理主义的一种形式。该理论的基础是，所有的实体（和概念）都是物质的一种构成或者表达，并且，所有的现象（包括意识）都是物质相互作用的结果，在意识与物质之间，物质决定了意识，而意识则是客观世界在人脑中的生理反应，也就是有机物出于对物质的反应。因此，物质是唯一事实上存在的实体。作为一个理论体系，唯物主义属于一元本体论。但其本身又不同于以二元论或多元论为基础的本体论。作为对现实世界的一种解释，它是唯心主义和心灵主义的一个对立面。

Materialism is a form of philosophical monism which holds that matter is the fundamental substance in nature, and that all phenomena, including mental phenomena and consciousness, are results of material interactions.

Materialism is closely related to physicalism, the view that all that exists is ultimately physical. Philosophical physicalism has evolved from materialism with the discoveries of the physical sciences to incorporate more sophisticated notions of physicality than mere ordinary matter, such as: spacetime, physical energies and forces, dark matter, and so on. Thus the term "physicalism" is preferred over "materialism" by some, while others use the terms as if they are synonymous.