1. Prefix meaning equal, like. 2. In chemistry, prefix indicating “isomer of” (isomerism); e.g., isocyanate vs. cyanate. 3. In immunology, prefix designating sameness with respect to species; in recent years, the meaning has shifted to sameness with respect to genetic constitution of individuals. [G. isos, equal]
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prefix denoting
equality, uniformity, or similarity.
Medical dictionary. 2011.