For forty-five years a team of linguists, primarily led by Christian Kay at the University of Glasgow, has laboured to produce the Historical Thesaurus of the Oxford English Dictionary. It contains historically organised synonyms for almost every word in the second edition of the OED, and in addition contains the whole range of Old English words that the OED does not define (the policy of the OED is not to include words that didn't survive into Middle English; the HTOED team wanted to include the entire history of the language). It is by far the largest thesaurus ever attempted in any language.

We use a dictionary to look up a word; we will use the HTOED to look up a sense or a number of senses. It has no real precedent, and although it does at first seem daunting, with perseverance and concentration it becomes approachable; then you can see