An empirical counterpart of a concept is called a

The empirical counterpart of a concept is a variable, the measurable form that a concept takes in research.

Operationalisation converts an abstract concept into a variable that can vary and be recorded.

Construct is itself an abstract idea, not its measurable counterpart.

Definition merely states meaning and does not supply measurement.

Hypothesis is a testable statement linking variables, not the counterpart of one concept.

Variables may be independent, dependent, control or intervening.