Definition
an imaginary creature like a horse with a single long horn on its head
a plan or suggestion that is completely impossible to achieve
Origin and usage
The word unicorn came into English in the 13th century via Old French, from Latin and Greek roots. The literal meaning is ‘single horn’ from the Latin ‘uni’ plus ‘cornu’.
Examples
Anyone who has been shopping in the past few years will have noticed that unicorns as a decorative motif are everywhere. Adorning everything from cakes and toys to jewellery and clothing, they have become the go-to image for our time. While for many centuries the word referred simply to the mythical beast with a horn in its forehead, it has recently acquired other meanings. A unicorn or unicorn company is defined as a start-up whose value has reached $1 billion or higher in a short space of time, the idea being that such companies are so vanishingly rare as to be comparable to a non-existent creature. An even more recent meaning refers to a plan or suggestion that is completely impossible to achieve, but nevertheless continues to be bandied about by those with an interest in promoting it.
Quotations
“I thought unicorns were more … Fluffy.”
(Terry Pratchett, Lords and Ladies)
“History suggests the 2010s will give rise to a super-unicorn or two that reflect the key tech wave of the decade, the mobile web.”
(Aileen Lee)
Related words
centaur, faun, satyr
View the full definition in the Macmillan Dictionary.