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Definition of Avogadro's number
1. Noun. The number of molecules in a mole of a substance (approximately 602,250,000,000,000,000,000,000). 
Medical Definition of Avogadro's number
1. 
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1. Noun. The number of molecules in a mole of a substance (approximately 602,250,000,000,000,000,000,000). 
1.