A generic name used for many dictionaries. The name was originally derived from the name of one of the first dictionaries of American English compiled by Noah Webster, but after Webster's death, and the passage of his original work into the public domain, there were many other copycat dictionaries published under this name or variations on it. The G. & C. Merriam Company had acquired the rights to Noah Webster's dictionary before this time, and had been publishing a series of dictionaries originally derived from it, and they were understandably upset over these copycats so close in name. At some point they tried to sue some of these dictionary makers over the name, but lost the suit, and as a result, now, anybody can use the name Webster on a dictionary.

The Merriam Co. changed the name of its dictionaries (and later the name of the company) to Merriam-Webster, and this is the company responsible for the dictionaries mentioned in yam's writeup.

See Also
Webster 1913
Merriam-Webster's New International Dictionary, Second Edition
Merriam-Webster's Third New International Dictionary
Merriam-Webster's Collegiate Dictionary, Tenth Edition