At the age of 70 in 1828, Webster published his dictionary; it sold poorly, with only 2,500 copies, and put him in debt.

In 1864, Merriam published a greatly expanded edition, which was the first version to change Webster's text, largely overhauling his work yet retaining many of his definitions and the title "An American Dictionary".

Merriam overhauled the dictionary again with the 1961 Webster's Third New International under the direction of Philip B. Gove, making changes that sparked public controversy.

Many of these changes were in formatting, omitting needless punctuation, or avoiding complete sentences when a phrase was sufficient.

The most notable change was the inclusion of the date of the first known citation of each word, to document its entry into the English language.

This dictionary is preferred as a source "for general matters of spelling" by the influential The Chicago Manual of Style, which is followed by many book publishers and magazines in the United States.

Its name was changed to "Merriam-Webster, Incorporated", with the publication of Webster's Ninth New Collegiate Dictionary in 1983.

[7][8] In one viral tweet, Merriam Webster subtly accused Kyle Rittenhouse of fake crying at his trial.

[9] In 1996, Merriam-Webster launched its first website, which provided free access to an online dictionary and thesaurus.

[11] The Merriam-Webster company once used a unique set of phonetic symbols in their dictionaries—intended to help people from different parts of the United States learn how to pronounce words the same way as others who spoke with the same accent or dialect did.

Hence, to enable computerized access to the pronunciation without having to rework all dictionaries to IPA notation, the online services of Merriam-Webster specify phonetics using a less-specific set of ASCII characters.

[5] Editors at Merriam spend about an hour a day looking at print sources, from books and newspapers to less formal publications, like advertisements and product packaging, to study the uses of individual words and choose things that should be preserved in the citation file.