struc·ture (strŭk′chər) n. 1. Something made up of a number of parts that are held or put together in a particular way: hierarchical social structure. 2. The way in which parts are arranged or put together to form a whole; makeup: triangular in structure. 3. The interrelation or arrangement of parts in a complex entity: political structure; plot structure. 4. Something constructed, such as a building. 5. Biology a. The arrangement or formation of the tissues, organs, or other parts of an organism. b. An organ or other part of an organism. tr.v. struc·tured, struc·tur·ing, struc·tures To give form or arrangement to: structure a curriculum; structure one's day.