In the game there is a convention, established in 1992, that we never play a word that has been played before, no matter how long ago. Here you can find all of the words dealt in Dixonary since Round 1, in which the word was keckle, together with the round number, and the name of the player who selected the word and dealt the round. An asterisk in the column Word abandoned or withdrawn indicates that the word was announced, but was withdrawn and a substitute played in its place, or (very occasionally) that the round could not be completed. In this case the players declare a redeal and start the round afresh, under the same round number as the uncompleted round.
This list has been maintained by various players over the years: Russ Heimerson (1945–2010), John Barrs, and currently Dan Widdis and Paul Keating.
To find out quickly if your candidate word is on the list, use the similarity check. This is the surest way not to miss a near match.
But if you insist on performing your own search, below is a link to a Google Sheet with the latest list.
The search tabs do a more thorough job than if you search for the exact word you have in mind, because that search may not reveal a closely related word, or another spelling of the same word, that has been played in the past. The search tabs allow wild-card searches to reduce the risk of missing such a word, and frequent dealers know to use them, but that sometimes does not occur to occasional dealers.
All members of the Google Group have access to the sheet, because it is granted to the group and not to individuals. If you are denied access, then log in to Google with the same address as you use in the group, or add your other address to your Google account.
Some players maintain that Google Sheets is hard to use, and are disinclined to learn. For them we provide the text files below.
These text files are updated weekly by automation from the Used Words List worksheet. Holding on to the downloaded copy after use increases the risk of using an old copy of the list. If you look for copies of these files in the Google Group, helpfully shared by players in the past, you will find them. But they are static copies attached to posts. You can't tell how out of date they are by looking at them. If you must have a text file, fetch the latest version from this site and direct others to do so.
The text files record used words in a format that was devised in 1990 for the Files section of the original CompuServe forum. The format was fixed, because at the time there were dealer support programs that were written to expect exactly that format. So they look like what they are: relics of a previous century.