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: the ovaries are used in reproduction. 
Sentence2: Egg released by the ovary.

A: ovaries
****
Q: Sentence1: Streams may start with runoff or water seeping out of a spring. 
Sentence2: Most water comes from precipitation.

A: water
****
Q: Sentence1: Humidity is moisture in the air. 
Sentence2: Lack of humidity causes low rainfall.

A:
Humidity
****