Final answer:
The combining form that means clumping is 'agglutino-' in biology.
Step-by-step explanation:
The combining form that means clumping is agglutino-.
For example, when discussing blood types, the process of clumping together of red blood cells that occurs when incompatible blood types are mixed is called agglutination. This term is derived from the Latin word 'agglutinare', which means 'to glue together'.
Other examples of words that use the combining form 'agglutino-' include agglutinogen (a substance that causes the clumping of cells, such as antibodies), and agglutinin (an antibody that causes clumping of cells).