What is the term for the fluid portion of the blood after coagulation (clotting) occurs?

Hint: Blood is a continually flowing liquid furnishing the body with nutrition, oxygen, and waste evacuation. Blood is for the most part fluid, with various cells and proteins suspended in it, making blood "thicker" than pure water. Blood is flowed around the body through veins by the pumping activity of the heart. In animals with lungs, blood vessel blood conveys oxygen from breathed in air to the tissues of the body, and venous blood conveys carbon dioxide, a waste product of digestion delivered by cells, from the tissues to the lungs to be breathed out.

Complete answer:
After coagulation, the fluid part of the blood is called serum. Plasma is the fluid part of blood prior to coagulation, and it includes all of the clotting agents dissolved in it. In this sense, the serum is distinct from plasma.

As we all know that blood must clot to heal wounds and also to prevent excessive blood loss. In order to do so, the platelets, which are small cell fragments, are drawn to the wound site and adhere by spreading several projections and releasing their contents. These substances activate other platelets and combine with other coagulation factors, which cause the blood to clot by converting fibrinogen, a water-soluble protein found in blood serum, into fibrin (a non-water-soluble protein). A platelet plug is formed when a large number of platelets aggregate and stick together at the wound site (also called a fibrin clot).

After coagulation, the liquid component of blood is called serum, which means that all of the clotting factors have been stimulated and used to form fibrinogen (insoluble fibrin that forms the clot). As the serum is fluid after coagulation, it will contain all of the electrolytes that aren't required for clotting. White blood cells, red blood cells, platelets, and clotting factors may not be present in the serum. The serum is similar to interstitial fluid in which the right balance of main ions acting as electrolytes which are required for normal muscle and nerve function. Proteins in the serum help to preserve pH and osmotic equilibrium while also giving viscosity to blood.

Therefore the answer is ‘Serum’.

Note: It is very important to note that plasma will contain all the coagulation factors and antibodies. Whereas, the serum is a component of plasma that is missing all the factors required for coagulation as they are all used up in the process of blood clotting or coagulation.