<p><strong>Noun</strong></p><ul><li>Biology: The living together of two dissimilar organisms, as in mutualism, commensalism, amensalism, or parasitism.</li><li>(Formerly) Mutualism.</li><li>Psychiatry: A relationship between two people in which each person is dependent upon and receives reinforcement, whether beneficial or detrimental, from the other.</li><li>Psychoanalysis: The relationship between an infant and their mother in which the infant is dependent on the mother both physically and emotionally.</li><li>Any interdependent or mutually beneficial relationship between two persons, groups, etc.</li></ul>