Critical thinking (CT) is a flourishing concept that has been developing throughout the fields of both nursing education and practice. In fact, every person thinks in his or her own way that is varied among individuals; it is the nature of human mankind to do so. Nevertheless, much of our thinking might be subjective, indefinite, limited, conventional or inclusively narrow-minded. CT is an essential expected competency of nurses at all levels of education and practice, and is a required component of nursing programs, including critical care nursing training programs (National League for Nursing Accrediting Commission, 2006). Various authors have accentuated the need for nurses to be able to think critically in order to apply the proper theoretical knowledge in their clinical skills, using reasonable judgments in providing high standards of quality patient care. Yet, each author has defined CT in a different way. Luckowski (2003) reported that CT is basically the ability to analyze and appraise evaluations. The researcher has been surprised by what CT is and what it means to nursing graduates and practicing nurses. So, he searched an extensive literature related to this concept and conducted this study to further explore the definition of CT from the perspective of novice critical care nurses based on their experiences in their first nursing orientation. Based on the participants' perceived definitions of CT, this study will provide data that could influence the implementation of future nursing orientation programs conducive to CT development. The knowledge generated from this study could benefit critical care nurses and nurse educators, and contribute to the enhancement of the patients' outcomes. It will also be a contribution to the research and literature in the discipline of CT in nursing education.