The successor to Merriam-Webster's New International Dictionary, Second Edition. An unabridged dictionary first published by Merriam-Webster in 1961 which was controversial at the time, because it was the first widely-available descriptive dictionary of American English, which attempted to archive the language as it is used. Previous dictionaries tended to be prescriptive, attempting to define what was to be considered standard.

NI3 turned the world of lexicography on its head by, for the first time, including large amounts of slang, colloquial usages, and words and word usages that are considered incorrect, improper, or informal, but are used anyway. (In general, these are tagged as such, so the dictionary is still somewhat prescriptive.) At the same time, Merriam-Webster also eliminated thousands of obsolete words nobody uses any more, reducing the overall size of the dictionary by a bit.

This great dictionary is now available on CD-ROM. See also Errors in the NI3 on CD-ROM.