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Definition 2024

portolan ‎(plural portolans)

(nautical) A chart of European navigable waters based on descriptions of coasts. [from 18th c.]
- 2012, Simon Garfield, On the Map, Profile Books 2012, p. 110:
  Portolans are as old as the European mariner's magnetic compass, and for about two centuries the two depended on each other for the growth and safe passage of Mediterranean trade.