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.