When the antiphrasal use is very common, the word can become an
auto-antonym,[3] having opposite meanings depending on context.
For example, Spanish dichoso[4] originally meant "fortunate, blissful" as in tierra dichosa, "fortunate land", but it acquired the ironic and colloquial meaning of "infortunate, bothersome" as in ¡Dichosas moscas!, "Damned flies!".
Etymology
Antiphrasis is a Greek word which means 'opposite words'.[5][6]
Antiphrasis as euphemism
Some
euphemisms are antiphrasis, such as "Eumenides" 'the gracious ones' to mean the
Erinyes, deities of vengeance.
Examples
"Take your time, we've got all day", meaning "hurry up, we don't have all day".
"Come into my parlour, said the spider to the fly" appears to be an invitation, but is in fact a threat.
"Tell me about it", in the sense of "don't bother, I already know".
"Great!", an exclamation uttered when something unpleasant had happened or is about to happen.