poin·ci·an·a (poin?s?-?n??, -ä?n?)n. The royal poinciana.[New Latin Poinci?na, former genus name, after M. De Poinci, 17th-century governor of French West Indies.]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.poinciana (?p??ns????n?) n (Plants) any tree of the tropical leguminous genera Caesalpinia (formerly Poinciana) having large orange or red flowers. See royal poinciana[C17: New Latin, named after M. de Poinci, 17th-century governor of the French Antilles]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014poin?ci?an?a (?p??n si?æn ?) n., pl. -an?as. 1. royal poinciana. 2. any of several tropical legume trees of the genus Caesalpinia, having showy red, orange, or yellow flowers. [1725?35;