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: Germination depends on the seed coat. 
Sentence2: the force of water causes germination with the emergence of a root.
Example Output: Germination

Example Input: Sentence1: Energy enters ecosystems in the form of sunlight or chemical compounds. 
Sentence2: Energy enters ecosystems in the form of photons.
Example Output: Energy

Example Input: Sentence1: the Earth being tilted on its axis causes ones side of the Earth to receive less energy from the Sun than the other side. 
Sentence2: Solar energy is power.
Example Output:
energy