designed to be applied with heat and pressure, as by an iron: an iron-on patch for pants.
a design, patch, or the like, applied by ironing on.
Origin of iron-on
First recorded in 1955–60; noun use of verb phrase iron on
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Online Etymology Dictionary, © 2010 Douglas Harper