"completely careless" is a grammatically correct and acceptable phrase in written English.
It is often used to describe someone's behavior or actions that display a lack of attention or concern. Example: Despite multiple warnings from his boss, Peter was completely careless when it came to handling important client documents. As a result, he lost a valuable account for the company.
It was completely careless and based totally in laziness on my part...
"Vale and BHP were completely careless in terms of prevention," said Sandra Cureau, an assistant prosecutor general in Brasília, Brazil's capital.
My initial impression was that this was a man who was completely careless about his appearance, but I eventually concluded that the scrupulous inattention to wardrobe and grooming was of a piece with his refusal to fly on airplanes (visiting America from his home in Berlin, he travels by ship) or to carry a cellphone.
Remember not to be TOTALLY careless.
Since no software is ever completely free of errors, be it careless minor oversights or the results of serious design problems, it is therefore expected that with prolonged and systematic testing, N x) will increase with x.
One of her contemporaries was struck by how completely Lawrence had captured Farren's "arch, careless, spirited, elegant and engaging" presence.
In an e-mail message sent to The Associated Press on Sunday, Mr. Craig said the latest accusations were "completely false" and criticized the paper as practicing careless journalism.
It's precisely because we have been careless with our traditions that we are so completely open to everybody else's.
A crooked business partner who took cash under the counter, compounded by my own careless accounting, had separated me from my business (a small chain of Bristol off-licenses) so completely that I was reduced to a salesman's existence.
"Completely original" was the epithet that got me, but either David or her copy editor was a bit careless, because it's an omble, not an ombre, chevalier — "a humble knight".
