It has been analysed a number of terms related to bacterium and virus of medical and veterinarian interest in order to know their origins and with the expectation that it will lead to a better understanding of the Microbiological terminology. In the case of bacteria, the etymological analysis encompasses to the taxonomic species level, meanwhile for virus it reaches to the family level with some familiar genera.

In bacteria, the genera prefixes are almost always Greek roots or the name modification of researchers related to the bacterium. The suffixes could be Greek or Latin and they refer to the morphological bacteria types. For the species mostly Latin roots are used and they represent geographical characteristics such as host, target organ, etc.

Regarding to virus, the family name has Greek prefixes, whereas the suffixes are always related to virus (viridae) which is a Latin term.

In any case, every living organism studied is given with a brief description about its pathological effects.

We hope the usefulness of this work as teaching material in Microbiological programmes.