The dictionary covers the current vocabulary of standard written and spoken English. New terms or new uses of existing terms are therefore included at the expense of obsolete ones. The cut-off point is set at 1755 and is informed by usefulness: words obsolete before this time, unless found in the well-known works of major authors, are omitted.
This electronic version comprises the text of Webster's Third New International Dictionary, Unabridged, published in 1961, and subsequent updates which take account of current usage. The Merriam-Webster company has continued to update its files since publication of Webster's Third New International Dictionary. The source data for this electronic version of Webster's Unabridged was obtained in 1996 and so includes additional material and addenda included since publication of both the original 1961 edition and the updated 1993 edition. This version appears in electronic form for the first time.