1. A clumped mass of material formed by erythrocytes and leukocytes: Agglutination occurs when bacteria or red cells are lumped together by antibodies or agglutinins.
2. The act or process of agglutinating; adhesion of distinct parts: The agglutination of the porcelain figure didn't work because it fell apart again.
3. In linguistics, the formation of words from morphemes that retain their original forms and meanings with little change during the combination process: Agglutination can be exemplified by the words countlessness, ceaselessness, and colorless.