It's the world's first historical thesaurus,
grouping words by meaning and by date.
And it survived fire,
lack of funds and the death of some of its founders.
Tomorrow the work will finally be unveiled to academics
prior to its publication in October.
Professor Christian Kay of the University of Glasgow
began work on the project as a 28-year-old research assistant.
She's now 69
and thinks it will be invaluable to scholars
not just of linguistics
but of cultural and social history.
"You know,
if you're interested in something like clothes,
it's very interesting to
see what people have been wearing for the last 1,300 years.
So I was looking at a whole list of words
to do with trousers and there were words
that would never have occurred to you probably
that these words meant trousers."
That's where a thesaurus beats a dictionary,
she says.
But it's much harder work to compile.
In the early days they simply wrote the words
on slips of paper and grouped them in different ways.