The Oxford English Dictionary may disappear from bookshelves because future editions could be too big to print.
Only an online format would be practicable and affordable as the third edition is expected to be twice the size of the current version, according to its publishers.
Dubbed OED3, it is already running 20 years behind schedule - and compilers are not expected to finish until 2034.
OED editor Michael Proffitt said the internet had slowed the process by creating so much more source material.
"A lot of the first principles of the OED stand firm, but how it manifests has to change and how it reaches people has to change," he told Country Life magazine.