Qu’Ap·pelle River (kw?-p?l?) A river, about 430 km (270 mi) long, of southern Saskatchewan and southwest Manitoba, Canada, flowing east to the Assiniboine River.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.