A·qui·nas (?-kw??n?s), Saint Thomas 1225-1274. Italian Dominican friar, theologian, and philosopher. The most influential thinker of the medieval period, his philosophy combined Aristotelianism and elements of Neoplatonism within a context of Christian thought. His works include the Summa contra gentiles (1259-1264) and the Summa theologiae or theologica (1266-1273).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.Aquinas (??kwa?n?s) n (Biography) Saint Thomas. 1225?74, Italian theologian, scholastic philosopher, and Dominican friar, whose works include Summa contra Gentiles (1259?64) and Summa Theologiae (1267?73), the first attempt at a comprehensive theological system. Feast day: Jan 28. See also ThomismCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014A?qui?nas (??kwa? n?s) n. Saint Thomas, 1225??74, Italian scholastic philosopher. A?qui?nist, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.