Gains·bor·ough (g?nz?bûr??, -b?r-?), Thomas 1727-1788. British portrait and landscape painter. His masterpieces include The Harvest Wagon (1767) and The Blue Boy (1770).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.