Final answer:
The body water that bathes most cells excluding blood cells is called the interstitial fluid (IF), which is a component of the extracellular fluid.
Step-by-step explanation:
The portion of the body water outside of cells that bathes most cells of the body is known as the interstitial fluid (IF). This fluid is part of the extracellular fluid (ECF) which is located between the cells. The intracellular fluid (ICF), on the other hand, resides within the cells, comprising about 60 percent of the body's total water content and is mainly found in the cytosol/cytoplasm.
Besides intracellular and interstitial fluids, the ECF also encompasses blood plasma, which differs from interstitial fluid in terms of protein concentration and ionic composition. The ECF provides an environment that supports cellular function by facilitating the transport of materials between cells and the blood plasma through the capillary walls.