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: Osteoporosis is a disease in which osteoclasts are more active than osteoblasts.
Sentence2: a thinning and weakening of bone is a disease in which osteoclasts are more active than osteoblasts.

A: active
****
Q: Sentence1: Most major Atlantic hurricanes start as small disturbances moving westward off Africa.
Sentence2: When something that starts as a small disturbance moving westward off Africa then moves over land, it will decrease in strength.

A: Africa
****
Q: Sentence1: boiling means change from a liquid into a gas by adding heat energy.
Sentence2: boiling changes a liquid into steam.

A:
liquid
****