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: First, the bottle is calibrated with a graduated cylinder. 
Sentence2: calibration is performed with a cylinder.
[A]: calibrated


[Q]: Sentence1: An accounting period is simply a period of time. 
Sentence2: seconds are used to measure a period.
[A]: period


[Q]: Sentence1: Invertebrates are animals that lack a vertebral column, or backbone. 
Sentence2: Snails and slugs are invertebrates.
[A]:
Invertebrates