The nineteenth letter of the English alphabet, called ess and written in the Latin script.
An axiomatic set theory, developed by logician George Boolos, in which several of the axioms of ZF are derivable as theorems.
A size of a sheet of paper resulting from folding and cutting a sheet of paper into sixteenths (3.25"-5" x 5"-6.25").
A book consisting of pages of that size.