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: Very often their only metal object in the house is a cooking pot or a knife. 
Sentence2: sharpening a knife causes it to change shape.
Example Output: knife

Example Input: Sentence1: Flies are insects with two wings. 
Sentence2: Flies are arthropods with two wings.
Example Output: Flies

Example Input: Sentence1: when a river floods , that river deposits soil in flood plains. 
Sentence2: when a river floods, that river deposits silicate minerals in flood plains.
Example Output:
deposits