The first word in an organism scientific name

Biological Classification goes from broadest to most specific.

Here is the order:

Life

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

When saying the scientific name of an organism we obviously do not say each of their 9 names, instead organisms are referred to as Genus Species. For example a Blue whale's Genus is balaenoptera and its Species is musculus. So we call it Balaenoptera musculus.