Alms-Basket of Words
The introduction to my edition of Roget's International Thesaurus is written by Ivor Brown, and explains the role of a thesaurus. Given that Peter Roget's book has been around in various forms since 1805, it's a bit weird that he should have to explain it, but he does manage to devise a nice description, concluding that a thesaurus is "what one of Shakespeare's characters called 'an alms-basket' of words and its verbal bounty amply justifies the name of a treasure."
The phrase "an alms-basket of words" is from Love's Labour's Lost, V.i, and is most memorable because it comes just a few lines above where Costard uses the word honorificabilitudinitatibus, which is meant to be the longest word that Shakespeare uses in any of his plays. But Costard is actually just giving it as an example of a long word, so the longest words that Shakespeare actually uses are anthropophaginian, indistinguishable, and undistinguishable. The first of these was used in Merry Wives, and the latter two are used in Tro. and MND (to follow standard abbreviations).
Thesauri are much better than dictionaries for verbophiles because the chance of stumbling on a new awesome word is so much higher, but even so I think they could be improved quite a bit. Synonyms are much more complicated than their hierarchical arrangement in Roget's (which is still a tremendous acheievement) suggests, and it would be a great person who could come up with a more granular thesaurus where all of the words are arranged in a kind of multi-dimensional venn diagram according to various relationship types between synonyms.
Because language changes so fast, there really just need to be more people working on lexicography. If the government sponsored the OED or gave it huge amounts of lottery funding, and then put the whole lot in the public domain much like the CIA Factbook, that might help matters a bit—not that the OED isn't doing a good job already. The problem with govenment sponsorship, too, is that it would make it look like an Académie Française style authoritative nightmare, when the goal is rather to be as descriptive as possible.
Perhaps as Natural Language Processing becomes more advanced, the initial word gathering phase of lexicography at least will be made easier.
Cite: Palmer, S.B. (2005). "Alms-Basket of Words", in: What Planet is This?
Archival URI: http://inamidst.com/notes/almsbasket