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.

Sentence1: Mitosis is cell division. 
Sentence2: Chromosomes are the form of the genetic material of a cell during mitosis.
Mitosis

Sentence1: a flashlight requires a source of electricity to produce light. 
Sentence2: Flashlights provide the safest emergency lighting source.
flashlight

Sentence1: Weather changes from season to season. 
Sentence2: Earth orbiting the Sun causes weather changes.

Weather