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: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Phototropism means growing toward the energy of light.

A: phototropism
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Q: Sentence1: Enveloped viruses make their own membranes. 
Sentence2: Some viruses make their own membranes.

A: make
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Q: Sentence1: Salamanders are a type of amphibian. 
Sentence2: Some amphibians use their sense of smell to find a mate.

A:
amphibian
****