Proplasm is a term typically used in biology to refer to the living substance found in all cells. Some synonyms for proplasm include protoplasm, cytoplasm, and cell substance. While these words are often used interchangeably, they do have slightly different meanings. Protoplasm specifically refers to the living matter within a cell, including its nucleus. Cytoplasm refers to the entire substance of a cell, including its organelles. Cell substance is a broader term that refers to the overall matter of a cell, including both living and non-living components. Regardless of the specific term used, proplasm and its synonyms are essential components of all living organisms.