1. characteristics or qualities that determine the nature of a mental experience (sensation or perception) and make it distinguishable from other such experiences, so that, for example, the experiencer differentiates between the sensations of heat and cold. Qualia bear some conceptual relationship to the empiricist notion of primary qualities and secondary qualities; in some systems, however, they take on the quality of basic or fundamental units of experience. Other thinkers, primarily those in the materialist tradition, reject the notion of qualia as an unnecessary construct with little explanatory value.

2. the phenomenal, conscious states or feelings specific to each emotion. The ineffable phenomenal states of anger, happiness, fear, sadness, and so on are qualia of affect.