invisible ink(redirected from invisible inks)
Ink that is colorless and invisible until treated by a chemical, heat, or special light. Also called sympathetic ink.
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.
(Chemistry) a liquid used for writing that does not become visible until it has been treated with chemicals, heat, ultraviolet light, etc
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a writing fluid that is invisible until treated, as by heat or chemicals.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.