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: Chordates have a complete digestive system and a closed circulatory system. 
Sentence2: All chordates are vertebrates.
[A]: Chordates


[Q]: Sentence1: plant requires seed dispersal for reproduction. 
Sentence2: plants are pollinated by birds.
[A]: plant


[Q]: Sentence1: poison causes harm to living things. 
Sentence2: Lead poisoning is one of the more common poisonings in birds.
[A]:
poison