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.
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Question: Sentence1: Runoff water is wasted water. 
Sentence2: Streams may start with wasted water.

Answer: wasted


Question: Sentence1: Smoking accelerates the aging process. 
Sentence2: smoking accelerates the death of cells.

Answer: Smoking


Question: Sentence1: landfills have a negative impact on the environment. 
Sentence2: waste has a negative impact.

Answer:
impact