The phrase "a serious set back" is not correct due to the incorrect spelling of "set back," which should be "setback" as one word.
You can use it when discussing a significant obstacle or difficulty that hinders progress or success.
Example: "The unexpected loss of funding was a serious setback for the project, delaying its completion by several months."
Alternatives: "a major obstacle" or "a significant hindrance."
But the fact that it was cut at such short notice has been a serious set back for many co-operatives.
Speaking on Sky News during a visit to London, Hoshyar Zebari admitted that the militants were a "mortal threat" to Iraq and that the fall of Mosul was a serious set back to the Iraqi security forces.
The Senate's confirmation last night of Michael Mukasey for Attorney General was a devastating failure of leadership, and a serious set back in our fight to take back America.
The company's reserves are at its lowest and unforeseen catastrophes, though they may not be fatal, but could cause a serious set back.
If Kobane falls it will be a serious set-back for the Kurds.
In 2005 Thomas suffered a serious set-back when he needed his spleen removed after a crash in Australia, while another bad fall in a time trial in Italy in 2009 saw him break his pelvis.
In putting together this LAYERS piece, Marlyn experienced some serious set backs.
It was just weeks after the party had suffered the serious set-back of the 2010 midterm elections and, knowing that Obama's own hopes of re-election depended in no small part on Iowa, about 25 people from the Des Moines neighborhood of Beaverdale came together over beers and martinis to pledge themselves to do all they could to secure his second term.
Always remember that the greatest successful people in the world, have themselves suffered some of the most serious set-backs.
Despite serious set-backs at Colenso, Stormberg, Magersfontein, and Spion Kop in January and with Ladysmith still under siege the British mounted a five division counter-invasion of the Orange Free State in February.
