Am·brose (?m?br?z?), Saint ad 340?-397. Writer, composer, and bishop of Milan (374-397) who imposed orthodoxy on the early Christian Church.Am·bro?sian (?m-br??zh?n) adj.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.