fi·a·cre (f?-ä?kr?)n. A small hackney carriage.[French, after the Hôtel de Saint Fiacre in Paris.]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.fiacre (f????kr?) n (Automotive Engineering) a small four-wheeled horse-drawn carriage, usually with a folding roof[C17: named after the Hotel de St Fiacre, Paris, where these vehicles were first hired out]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014fi?a?cre (Fr. ?fya kr?) n., pl. fi?a?cres (Fr. ?fya kr?) a small horse-drawn carriage. [1690?1700;