I like this - it's very well executed - even though I'm not sure exactly how it could be used within a Functional Skills English classroom. I receive many suggested links and mostly ignore them (due to them not being free or not being useful for Functional Skills). However, I always have a soft spot for "Words of the Day" as they can make great warm up activties at almost any level.
In addition to its "Word of the Day" feature the Unscramblerer.com dictionary also has great features for fans of Scrabble, Wordle, crosswords and other word games. For ideas on how to include Words of day in your teaching take a look at my 30 Words of the Week plan and my 7 Words of the Week PPT. Warning: both were written almost 20 years ago (!) for my then adult literacy classes but they're still full of useful ideas.