1. Microbiology. Transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between the donor cell and the recipient cell. It is through this process that resistance to antibiotics can be transferred from one bacterial cell to another.
2. Biology. A type of sexual reproduction in ciliate protozoans for achieving exchange of genetic material.
3. Chemistry. Series of alternating single bonds and double bonds in a chemical compound.