Answer:

We use Latin, and sometimes ancient Greek, as the basis for a universal scientific language, and occasionally, words from other languages. We use these 'dead' languages because the word meanings don't change the way they sometimes do in English and other modern languages.

Explanation:

They were invented because new words were needed to name newly described structures. For hundreds of years they had to be in Latin (or Greek) because books about biology and medicine were written in Latin (with a few entries in Greek), which was the international language of science.