n. in the thought of German philosopher Martin Heidegger (1889–1976), that aspect of Dasein (being-in-the-world) that is constituted by a person’s engagement with the world immediately around him or her. The term was introduced into the vocabulary of psychology chiefly through the work of Swiss existential psychologist Ludwig Binswanger (1881–1966). Compare Eigenwelt; Mitwelt. [German, literally: “around world”]