Which term refers to something that actually exists and has been observed?

The term that refers to something that actually exists and has been observed is a fact. In scientific contexts, a fact is a statement that can be verified through observation or empirical evidence. It is established through repeated measurements and confirmations, making it a foundational element in the scientific method.

A hypothesis is an initial assumption or educated guess that can be tested through experimentation. It is not yet verified and remains unproven until supported by data. A theory is a broader explanation that incorporates and synthesizes multiple facts, hypotheses, and laws, offering a comprehensive understanding of a phenomenon based on substantial evidence. An assumption is a belief that is taken for granted without requiring proof, often serving as a starting point for further inquiry.

Understanding the distinction between these terms helps identify what constitutes verified knowledge versus preliminary ideas or broader interpretations within scientific discourse.