According to a usage becoming popular since last week's military coup in Egypt, a military coup isn't one provided you approve of it. Thus Mohamed ElBaradei, in an interview with Der Spiegel:
SPIEGEL: Mr. ElBaradei, you opposed the authoritarian rule of former President Hosni Mubarak. Now, it appears that you will play a significant role in the interim government put in place after military leaders overthrew the democratically elected president of Egypt. Should a Nobel Peace Prize laureate be part of such a coup?
ElBaradei: Let me make one thing clear: This was not a coup. More than 20 million people took to the streets because the situation was no longer acceptable. Without Morsi's removal from office, we would have been headed toward a fascist state, or there would have been a civil war.
The political motivation for the usage in some quarters is clear. As Ian Black reports, President Obama wanted to '[avoid] use of the C-word to stave off the risk that US financial aid to a strategically important Middle Eastern ally might be cut off by Congress'. And according to Magdi Abdelhadi:
Almost no one in Egypt - except the Muslim Brothers and their closest allies - views the military's intervention as a coup. And no one believes the army wants to rule...
The army has said it has a new plan to move Egypt out of the current impasse. Let us hope it does not repeat past mistakes. If it does now take the reins of power temporarily, it must create a level playing field so that all political players, including the Islamists, can continue to take part in Egyptian politics.
Egypt's ambassador to the US also denies that 'the military's ouster of President Mohamed Mursi constituted a coup'.
Commentators who support the removal of Morsi by the Egyptian army have fallen in with these locutions. Here's Amira Nowaira:
The overthrow of President Morsi may seem like a military coup. But to all intents and purposes it is not. The call for Morsi's ousting was made by millions of Egyptians who went out on the streets for four days in a row, raising Egyptian flags and chanting one word directed at him: "Erhal", meaning, "leave, depart".
However, one is not bound to conflate the issues of meaning and justification. One could hold that this was a military coup whether justified or not - and therefore even if it was justified. I don't intend to comment on the legitimacy or otherwise of Morsi's removal. What counts as legitimate during a revolutionary process is often one of the main things in contention and is only settled post hoc. For this action to have been justified I would think that free elections now have to follow in short order, from which the Islamists have not been excluded. But, in any event, whether there has been a coup or not doesn't depend on whether one believes it was - or will turn out to have been - for the good of the country.