Word Origin and History for tertiary Expand. adj. 1650s, of the third order, rank, degree, etc., from Latin tertiarius of or pertaining to a third, from tertius third, a third, from root of tres three (see three).
Water and Fluid retention in legs, also known as edema, is a medical condition caused by abnormal accumulation of water or fluids in the bodyâs tissues. Though excess water can be accumulated anywhere in the body, the most common areas are the ankles and legs.
Some conditions that may cause swelling in just one leg include: 1  Blood clots. Clots can cause pooling of fluid and may be accompanied by discoloration and pain. 2  Weakened veins. Varicose veins, or veins whose walls or valves are weak, can allow blood to pool in the legs. 3  Infection and inflammation.