OUP says it will be the largest thesaurus in the world
The world's largest thesaurus is due to be published this autumn, Oxford University Press has said.
The project began in 1965 and will include almost the entire vocabulary of the English language.
The work was nearly destroyed in a fire in 1978, but despite the building being gutted, a metal filing cabinet protected the files.
A spokesman said the final tome would contain over 230,000 categories with 800,000 meanings.
The thesaurus was nearly completed in 1980, but the team decided to include words from updated versions of the Oxford English Dictionary.
This added almost 30 years more work to the project.
The finished book will be twice the size of the current Roget's Thesaurus when it is published in October.
Professor Christian Kay, 69, one of four co-editors, began working on the book in the late 1960s when she was 27.
She said: "I didn't think at the time I would be involved 40 years later.
"We started using Roget's classifications, but it soon became apparent that wasn't adequate, as it wasn't detailed enough.
"Then we virtually started from scratch with a new system. That's why it took so long."
The thesaurus is divided into 354 categories covering subjects including leisure, education, faith and philosophy.
The eventual plan is to link the project to the online version of the Oxford English Dictionary, but no date has been set for this.