Mindfulness is an emerging concept in many professions and spheres of social life. However, mindfulness (or sati in Buddhism) can connote many plausible meanings. Thus, the concept is not easily defined and the definitions provided in the literature easily confuse the reader. Some mindfulness researchers offer definitions whereas others do not and take the definition of mindfulness for granted. Beyond the problem of defining mindfulness, the fact that the phenomenon is of great interest to various disciplines, each of which has its own theoretical and methodological approaches, different authors use different terms in describing this phenomenon. In the present article 33 definitions of mindfulness were extracted from a pool of 308 peer-reviewed full-length theoretical or empirical articles written in English, published between 1993 and March 2016, after systematic searches in Google Scholar, PsycARTICLES, and SocINDEX. The definitions were analyzed with a particular focus on the defining attributes or core elements of the concept of mindfulness. The analysis yielded 4 core elements of awareness and attention, nonjudgmental attitude, external events, and cultivation. Furthermore, an additional core element emerged from this analysis as being absent in Western definitions of mindfulness. This formed the basis for formulation of a new definition of mindfulness with an emphasis on ethical-mindedness. We argue that this core element is instrumental in filling in the gap that exists in current Western definitions, and with highlighting this element we hope to bridge the Western and Buddhist notions of mindfulness.