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: a flower 's purpose is to produce seeds. 
Sentence2: Every job has meaning and purpose.
purpose

Sentence1: Heat production is increased by shivering and non-shivering thermogenesis . 
Sentence2: Heat production occurs when many muscles contract a little bit all at once.
Heat

Sentence1: Magnets are used in compasses. 
Sentence2: magnets can be used to determine direction.

Magnets