Abbreviation for
Savings and Loan Association, a type of bank. Modern references to S&Ls will likely evoke memories of the
savings and loan crisis of the 1980s and 1990s, when many American S&Ls crashed, causing great trouble for consumers and prompting an astronomically expensive government bailout (~$5X10^12).
A more complete description can be found at the
Savings and Loan Association node.