The phrase "vacuous speech" is correct and can be used in written English.
It is often used to describe speech that is empty and lacks substance or meaningful content. Example: The politician's campaign rally was filled with vacuous speech, with no real plans or solutions being offered to the public.
The President's initial response consisted of a few tweets, a phone call to Rick Scott, the N.R.A. favorite who serves as governor of Florida, and a short, vacuous speech delivered from the White House Diplomatic Room on Thursday morning, during which he told the parents, teachers, and students of Marjory Stoneman Douglas High, "We are here for you.
"The markets were hoping for detailed programs, and they expressed their disappointment with Geithner's vacuous speech with a large sell-off," writes Barofsky, 42, a former Manhattan federal prosecutor.
But such moments were rare among the daily procession of pomp and vacuous speeches.
(If he's pressed for time, he can just watch Huntsman's wispy and vacuous announcement speech and contrast it with, oh, just about any public appearance Christie has made over the past two years).
Nice, if vacuous, words were spoken all round.
Arguably a new low in spiritual rhetoric was achieved, quite amazingly, by the vacuous and self-preening speech Matthew McConaughey delivered in accepting his Academy Award for Best Actor in a Leading Role.
The speech was dismissed as vacuous by the Conservatives, but welcomed by most wings of Miliband's own party.
In fact, most of the points in the PM's debriefing were so vacuous they were recycled from a speech she gave back at the start of her tenure: that there will be no second referendum, and that parliament won't get a vote on the deal.
Labour's home secretary, Tony Blair, was put up to attack it, and, in an uncharacteristically irritable speech, called the third way "vacuous".
He does this through an inspirational speech, but Britta sees through his vacuous rhetoric and asks him to leave.
Cheesy, vacuous - and occasionally brilliant, this was indeed the speech of Gordon Brown's life... this was the product of desperation, it's tactics a measure of how bad things have got and how far the PM is willing to go to cling to power.
