aitch (?ch)n. The letter h.[French hache.]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.aitch (e?t?) nthe letter h or the sound represented by it: he drops his aitches. [C16: a phonetic spelling]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014aitch (e?t?) n. the letter H, h. [Middle English ache