Pont·char·train (p?n?ch?r-tr?n?), Lake A lake of southeast Louisiana north of New Orleans. A causeway links New Orleans with the region north of the lake.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Pontchartrain (?p?nt???tre?n) n (Placename) Lake Pontchartrain a shallow lagoon in SE Louisiana, linked with the Gulf of Mexico by a narrow channel, the Rigolets: resort and fishing centre. Area: 1620 sq km (625 sq miles)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Pont?char?train (?p?n t??r?tre?n) n. Lake, a shallow extension of the Gulf of Mexico in SE Louisiana, N of New Orleans. 41 mi. (66 km) long; 25 mi. (40 km) wide. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.