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: An accounting period is simply a period of time. 
Sentence2: seconds are used to measure a period.
[A]: period


[Q]: Sentence1: Infection is what ultimately leads to death. 
Sentence2: scraping oneself on a contaminated object may cause death.
[A]: death


[Q]: Sentence1: All complex living creatures, are organized by a nervous system . 
Sentence2: Most invertebrates are complex living creatures.
[A]:
complex