Italian law forbids giving children names that can "embarrass"
Italy's top court has banned a couple from naming their son Venerdi (Friday), saying such a "ridiculous" name could expose the boy to mockery.
The Cassation Court said the name - taken from Daniel Defoe's famous novel Robinson Crusoe - was associated with "subservience and inferiority".
The judges also ordered that the boy be renamed Gregorio - after the saint's day on which he was born.
The parents had argued that they should be free to name him as they pleased.
The couple, known only as Mara O and Roberto G, had pointed out that Italian celebrities quite often gave their children bizarre names, citing Chanel and Oceano as examples.
They now say that they will continue to call the boy Friday, describing it as "nice", and that they might even call their next child Mercoledi (Wednesday).
The Cassation Court upheld earlier rulings by lower courts that Friday was too reminiscent of the name of Robinson Crusoe's native servant in the classic shipwreck novel.
The verdict also triggered public debates across Italy on whether the judges were right to intervene.
Gian Ettore Gassani of the Italian Association of Matrimonial Lawyers backed the ruling.
Italian law mandated changes "when the child's name is likely to limit social interaction and create insecurity", Mr Gassani was quoted as saying by the Ansa news agency.
But Italian Journalist Alain Elkann said: "Friday seems a good name to me, it makes you think of Robinson Crusoe. I don't think it would create problems with the child's peers. It would have been different if they'd called him Friday the 13th."