instruction:
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.
question:
Sentence1: natural magnetism is used for pointing north by a compass. 
Sentence2: For the ordinary compass, align to the North direction.
answer:
north


question:
Sentence1: harming an animal species has a negative impact on the population size of that species. 
Sentence2: the rarity of a species increases harm to population exponentially.
answer:
harming


question:
Sentence1: Ships rely on active defense for protection. 
Sentence2: poisonous darts are used for protection by sea anemones.
answer:

protection