The phrase "a sizeable sum of" is correct and usable in written English.
It can be used when referring to a large amount of money or resources in a context where the exact figure is not specified.
Example: "After years of saving, she finally had a sizeable sum of money to invest in her dream home."
Alternatives: "a substantial amount of" or "a significant sum of".
Car hire desks will often seek to block a sizeable sum on your card for the duration of the rental if you don't buy their excess insurance.
SpatialOS was first announced over a year ago — and at the time, it was the first glimpse of what, exactly, Improbable, founded in 2012 by Cambridge academics Narula and Rob Whitehead, had been building with its significant funding (it's raised over $20 million to date, a sizeable sum for a stealthy startup out of London).
"Projects of this size and complexity have an impact on local areas, it is only fair that they should see a sizeable sum to compensate them," said John Osman, leader of the county council.
The Rhodes Must Fall movement said the statue of the man who was an ardent imperialist and left a sizeable sum to the college in his will, was representative of Britain's "imperial blind spot" and should be taken down.
"This is still a sizeable sum for a not-for-profit that is already dealing with the burden of increased costs, and I do not think the impact should be downplayed.
A sizeable sum for an exhibition was only seen by a very small audience, 800 residents of the village and the handful of press that attended the opening, but Mraz believes that it still had an impact.
The rangers are now paid a monthly salary of $250, a sizeable sum locally.
During the 1990s the couple invested a sizeable sum – including money from the sale of their previous home – with Equitable Life, before its spectacular fall from grace.
This grand scheme has also been a key part of his campaign to get his chosen successor, Dilma Rousseff, elected next month (Lula is constitutionally barred from standing again).Although $70 billion is a sizeable sum, it is only a fraction of the $224 billion that Petrobras intends to spend over its current five-year plan, which runs to 2014.
