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.

[Q]: Sentence1: freezing means changing from a liquid into a solid by reducing heat energy. 
Sentence2: Water freezes into ice when cooled.
[A]: freezing


[Q]: Sentence1: Smoking accelerates the aging process. 
Sentence2: smoking accelerates the death of cells.
[A]: Smoking


[Q]: Sentence1: Producers are organisms that produce food for themselves and other organisms. 
Sentence2: Parasites are organisms that obtain their food from living organisms.
[A]:
organisms