Dictionary Corner is the collective name for the lexicographer and guest celebrity, whose job is to both verify contestants' words and suggest longer or interesting words.
Now almost exclusively the role of Susie Dent, the role of lexicographer has traditionally been occupied by a member of the Oxford University Press or a member of the show's production team. On-screen, the lexicographer gives the final decision as to whether a word can be allowed or not.
The guest celebrities help Susie Dent find the longest words, and occupy a slot which they tell amusing anecdotes, perform anagrams, magic or other tricks, or add general entertainment to the proceedings. At present, this is between rounds 6 and 7.