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.

Sentence1: moss causes chemical weathering. 
Sentence2: Sphagnum moss mixed with peat moss.
moss

Sentence1: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.
important

Sentence1: a prism is used for refracting light. 
Sentence2: Light seems to travel in rays or beams.

light