Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Some viruses live in a dormant state inside the body. 
Sentence2: a virus can live in the brain.
viruses

Sentence1: plant reproduction requires pollination. 
Sentence2: Plant reproduction requires insects and hummingbirds.
plant

Sentence1: Scientists who find and study fossils are called paleontologists. 
Sentence2: Scientists who find and study old bones are called palentologists.

Scientists