Dictionaries purge their pages annually, adding new words and getting rid of the obsolete and offensive.
An article from the San Francisco Chronicle explains Merriam-Webster's process. Because languages are "living things" (metaphorically speaking), changes occur and need to be acknowledged. So, every ten years or so, the wordsmiths work on an updated edition. Hundreds of words (like "snollygoster") are cut, and even more (like "phat") are added.
The Oxford Dictionary also reexamines its definitions regularly. An article explains how the meaning of a word can change from year to year. Believe it or not, "nice" once meant silly, lazy, lecherous, and strange. Back in the 1300s, if a man told a woman he was "a nice guy," the lady was liable to slap him and run the other way (or so we presume).
Scrabble, the English major's game of choice, recently removed several words from its official dictionary due to their offensive nature. The Anti-Defamation League applauded the move, noting there is "no room on the board for prejudice."
While some words won't be missed, many antiquated terms are worth remembering.
via I did not know that yestersday!