Terra incognita or
terra ignota (
Latin "unknown land";
incognita is stressed on its second
syllable in Latin, but with variation in pronunciation in English) is a term used in
cartography for regions that have not been mapped or documented. The expression is believed to be first seen in
Ptolemy's
Geography c. 150. The term was reintroduced in the 15th century from the rediscovery of Ptolemy’s work during the
Age of Discovery. The equivalent on
French maps would be
terres inconnues (plural form), and some
English maps may show
Parts Unknown.