This paper offers a state-of-the-art working definition for the concept of Critical Thinking (CT hereafter) in an attempt to provide a framework for the development of an operational definition for this complex concept. Having studied various definitions and models, proposed for CT by major figures in the field, the key defining features of this rich concept were identified and classified. Based on these key descriptors, a working definition consisting of three main components namely Mind Analysis , Data Evaluation , and Thinking in Education has been proposed and then each dimension of this definition is defined and elaborated further so that the complexity of the concept could be framed in an extended model. The elaborated conception of CT proposed in this paper seeks to include the core elements of CT so that it can be expandable into an operational definition with measurable items. There are two main reasons for conducting this research: Firstly, CT has evolved into a multifaceted construct with a broad range of cognitive abilities and intellectual dispositions. Secondly, although CT has been recognized as a significant concept in education, its full potential has not been achieved yet.
