Merriam-Webster's Word of the Day for August 31, 2010 is:

dram • \DRAM\  • noun
1 : a unit of avoirdupois weight equal to 1/16 ounce 2 : a unit of apothecaries' weight equal to 1/8 ounce 3 : a unit of liquid capacity equal to 1/8 fluid ounce 4 a : a small portion of something to drink* b : a small amount

Example sentence:
The two of them don't have a dram of sense between them, so I'm not surprised that they got into so much trouble.

Did you know?
In avoirdupois weight -- that is, the system of weights commonly used by English speakers in North America and the United Kingdom -- a dram is equal to 1/16 ounce (1.772 grams). The word "dram" was borrowed from the Anglo-French and Late Latin word "dragme," which was originally used for a silver coin used by the ancient Greeks (now known in English as the "drachma") and for the coin's approximate weight. In the 16th century, English speakers also began using "dram" for a weight of fluid measure (also called a "fluid dram") equal to 1/8 fluid ounce, and more loosely for any small portion of something to drink. "Dram" is also used figuratively for any small amount, in much the same way as "grain" and "ounce."

*Indicates the sense illustrated in the example sentence.