Which term describes something that cannot be observed directly?

The term that describes something that cannot be observed directly is "phenomenon." A phenomenon refers to an observable occurrence or an event that can be subject to perception or interpretation. However, it often encompasses experiences or constructs that may not be tangible or directly measurable, such as emotions, thoughts, or societal trends.

In the context of psychological study, phenomena can reflect complex mental states or behaviors that researchers aim to understand, even if these states cannot be directly observed or quantified.

On the other hand, a variable is something that can vary and is often measured or observed. A model provides a theoretical framework to understand how various factors interact and predict outcomes. A hypothesis is a testable statement predicting the relationship between variables, which can also be observed or measured. Therefore, while all the other options relate to scientific inquiry, they are not inherently characterized by the inability to be directly observed like a phenomenon is.