The word "slip" is of Dutch origins, meaning a narrow cut or thin strip.
Today it is used in Dutch to refer mainly to cloth, for example the tail
of a coat.  (Websters and Van Dale Woordenboek.)  Slip's usage in New York
can be traced back to the Dutch colonial period, as Dutch remained the
primary popular language in the city until the mid-18th century, and in
rural areas such as Kings, Ulster, and other countries well into the 19th
century.

David Willliam Voorhees