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.

[Q]: Sentence1: Microbes are also called bacteria or microorganisms. 
Sentence2: Disease-causing bacteria have a negative impact on the body.
[A]: bacteria


[Q]: Sentence1: Fish are the first known true chordates. 
Sentence2: Fish are the first known animal with a backbone.
[A]: Fish


[Q]: Sentence1: a prism is used for refracting light. 
Sentence2: prisms refract light.
[A]:
refracting