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.

Example Input: Sentence1: a tape measure is used to measure length. 
Sentence2: Length The Base unit for length in the metric system is the meter .
Example Output: length

Example Input: Sentence1: soil is formed by weathering. 
Sentence2: Something described as loamy is formed by weathering.
Example Output: formed

Example Input: Sentence1: Evolution is a change in the characteristics of living things over time. 
Sentence2: Evolution is the process of adaptation.
Example Output:
Evolution