Aliquot is a noun that refers to a portion of a larger whole, especially a sample taken for analysis. 

Our word of the day has its origin in the Latin words alus (AH loose) meaning ‘one of two’ and quot (KO) meaning ‘how many.’ Often used in science, aliqot has been a part of the English language since the late 16th century. Example:

After examining the aliquot closely, Dr. Himmelman deduced that the swamp water wasn’t toxic. It’s amazing to me that they can make such a determination about the entire lake from a tiny sample.