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.

Ex Input:
Sentence1: Electrical currents cause magnetic fields. 
Sentence2: Electrical currents can cause objects to repel each other.

Ex Output:
Electrical


Ex Input:
Sentence1: Cnidarians have a hydrostatic skeleton. 
Sentence2: Jellyfish have a hydrostatic skeleton.

Ex Output:
hydrostatic


Ex Input:
Sentence1: Drought can be caused by less than normal rainfall. 
Sentence2: lack of moisture in the air causes Drought.

Ex Output:

Drought