mod·i·fy (m?d??-f??)v. mod·i·fied, mod·i·fy·ing, mod·i·fies v.tr.1. To change in form or character; alter.2. To make less extreme, severe, or strong: refused to modify her stand on the issue.3. Grammar To qualify or limit the meaning of. For example, summer modifies day in the phrase a summer day.4. Linguistics To change (a vowel) by umlaut.v.intr. To be or become modified; change.[Middle English modifien, from Old French modifier, from Latin modific?re, to measure, limit : modus, measure; see med- in Indo-European roots + -fic?re, -fy.]mod?i·fi?a·bil?i·ty n.mod?i·fi?a·ble 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.