Nomenclature is word is that define the system of naming things. Though there is no definite rule, the word is used only in science where it is used to name the species. This system of naming things was put forth by Linnaeus.
You might have come across the scientific name of things which is quite different from what we use in day-to-day life. The following example can make the meaning quite clear: we use the term 'human beings' to describe ourselves but when ever we need to describe ourselves in scientific terminology it is not good to use the term 'human beings' but there is a specific term that describe the species we belong to; we use the term Homo sapiens sapiens. The word 'Homo' describes the genus while the first 'sapiens' says about species and the second one describes the sub-species.
You might have come across the scientific name of things which is quite different from what we use in day-to-day life. The following example can make the meaning quite clear: we use the term 'human beings' to describe ourselves but when ever we need to describe ourselves in scientific terminology it is not good to use the term 'human beings' but there is a specific term that describe the species we belong to; we use the term Homo sapiens sapiens. The word 'Homo' describes the genus while the first 'sapiens' says about species and the second one describes the sub-species.