An operational definition is a clear, precise, and specific explanation of an abstract concept that is formulated in a way that allows a researcher to measure the concept empirically and systematically. It involves defining the concept in terms of the concrete, observable, and measurable indicators or procedures that will be used to represent it in a research study. For example, if a researcher is studying the concept of "happiness," an operational definition might be the score an individual reports on a standardised happiness scale, or the frequency with which they exhibit positive emotions during an observation period. Providing operational definitions is crucial for ensuring clarity, consistency, and replicability in research, as it specifies exactly how a concept will be measured and allows other researchers to understand and potentially replicate the study.