Typically a coup is defined by military usurpation of authority from a duly representative civilian government.
The diplomatic situation, given the arab uprisings of the last few year including the civil war in Syria, Libya's instability and now the subsequent chaos in Egypt and it's proximity to Israel, continue to require delicacy and thus there is an understandable hesitancy to reserve the term 'coup' from assignment to the Egyptian situation.
However, this is an unprincipled stance and such unprincipled stances frequently get the US labelled as hypocrites and continue to incite animosity toward US interests.
Military usurpation of authority, vicious bloodshed and a state of emergency; it's looking more like Tiananmen Square than Tahrir Square.
Declare the obvious: it's a coup!