Definition of "initialism" [initialism]

• An abbreviation consisting of the first letter or letters of words in a phrase (for example, IRS for Internal Revenue Service), syllables or components of a word (TNT for trinitrotoluene), or a combination of words and syllables (ESP for extrasensory perception) and pronounced by spelling out the letters one by one rather than as a solid word. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The plural of an initialism is the initialism plus s."
• "I recall a LONG time ago, when one of ALA's publication I think College & Research Libraries, but that could be wrong was redesigning its cover, they spent considerable time assuring that the new "initialism" graphic would not be sufficiently prominent to trigger a "title change.""
• ""initialism," the difference being it is an abbreviation using only first letters of words; an acronym being a new word created by the first letters, syllables or even arbitrary parts of the original words."