- is(o)-
- [Gr. isos equal] a prefix or combining form meaning equal, alike, the same, or uniform. In immunology, it indicates from a genetically identical individual (as an isograft) or existing in alternate forms in the same species (as an isoantigen). In chemistry it denotes a structural isomer; used in trivial names of alkanes to indicate a one-carbon branch next to the end of the chain, e.g., isohexane is 2-methylpentane; an isoalkyl radical has its free valence at the end of the chain opposite the branch, i.e., isohexyl is 4-methylpentyl.
Medical dictionary. 2011.