Contamination in the depth-psychology corpus occupies at least three distinct registers that intersect in revealing ways. In its most technically precise Jungian usage, contamination names the condition of the unconscious itself: a state of mutual interpenetration among archetypes that obtains wherever consciousness is weak or undifferentiated. Neumann states the formulation most plainly — ‘the single archetypes are not isolated from each other in the unconscious, but are in a state of contamination, of the most complete, mutual interpenetration and interfusion’ — and von Franz extends this into a theory of timelessness, arguing that the peculiar sense of oneness in mystical experience derives from ‘subliminal awareness of all-contamination in the unconscious.’ This psychological usage draws unmistakably on a second, archaic-religious register: the Greek concept of pollution (miasma), examined at length by Adkins, Rohde, Burkert, and Dodds. There, contamination is a quasi-physical force, non-moral in origin yet catastrophic in social consequence, transmitted by contact with blood, death, or violated taboo and requiring ritual katharsis. A third register appears in the therapeutic literature, where contamination denotes boundary failure in the analytic vessel — the seepage of the analyst’s unconscious contents into the field. Sedgwick’s index entry placing contamination beside countertransference and containment marks this clinical valence precisely. The term thus bridges archaic cosmology, structural unconscious theory, and the ethics of therapeutic practice.