System of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste.

(anatomy) The gastrointestinal tract.

(anatomy) the continuous system involved in the production and excretion of urine; the kidneys, ureters, urinary bladder and urethra

(anatomy) The passages, divided into an upper and a lower part, through which air enters and leaves the body, including the mouth, nose and nasal passages, pharynx, larynx, trachea, bronchi and conducting bronchioles, sometimes further including the respiratory bronchioles, alveolar ducts and alveoli.

(US) Any of many houses, of a similar or identical plan and design, built on a tract of land.

(US) A tract house.

(anatomy) A major collection of axons that transmits nerve impulses from the motor cortex to the spinal cord.

(biology) Ascending pathway in the white matter of the spinal cord, positioned closely to the lateral spinothalamic tract.

plural of tract home

(medicine) The path by which bile is secreted and delivered to the duodenum.