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.

[EX Q]: Sentence1: Osteoporosis is a disease characterized by a decrease in bone mineral density. 
Sentence2: a disease in which osteoclasts are more active than osteoblasts results in a decrease in bone mineral density.
[EX A]: bone

[EX Q]: Sentence1: exercise increases a body 's strength. 
Sentence2: Exercise is more than running and lifting.
[EX A]: exercise

[EX Q]: Sentence1: Animals may compete for territory, water, food, or mates. 
Sentence2: Tigers may compete for territory, water, food, or mates.
[EX A]:
compete