ill-use (?l?yo?oz?)tr.v. ill-used, ill-us·ing, ill-us·es To maltreat.n. (?l?yo?os?) Unjust or poor treatment; ill-usage.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.