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: if humans disturb animals in a location then those animals will move to a different location. 
Sentence2: The human being is self-aware.
Example Output: humans

Example Input: Sentence1: Flowers produce seeds for reproduction. 
Sentence2: flowers require dispersal for reproduction.
Example Output: Flowers

Example Input: Sentence1: Biomass is the total mass of organisms at a trophic level. 
Sentence2: Biomass is the total mass of living things at a trophic level.
Example Output:
Biomass