Astern 3 : Any distance behind a ship, as opposed to a-head, which is before her. Thus, when south is a-head, or on the line to which the stem is directed, north will be astern
William Falconer's Dictionary of the Marine, Glossary, Published by South Seas using the Web Academic Resource Publisher, London 1780. (http://threedecks.org/index.php?display_type=glos sary, (Mrtm - Brit) {583}