-some : A suffix added to a number to create a unit of quantity. For example, a foursome is a group of four. The suffix comes from the use of "some" as a pronoun meaning a number of individuals, as in "Some Like It Hot."
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}