Be in earnest. For example, He really means business with this deadline. This idiom uses business in the sense of “a serious endeavor.” [Mid-1800s]
Words nearby mean business
How to use mean business in a sentence
I was a little mystified at how benignly he responded to my questions about his business activities.
I mean, physically, mentally, you know, in every way, shape, and form.
This reporter knocked at the Wilkins home on Tuesday morning but received neither an answer nor the business end of a shotgun.The 7-Year-Old Plane Crash Survivor’s Brutal Journey Through the Woods|James Higdon|January 7, 2015|DAILY BEAST
“Competition is there, of course, but I think there is enough business for everyone as long as the demand is there,” he says.
Last March they gave Airbus a huge piece of new business, ordering 169 A320s and 65 of the slightly larger A321.Annoying Airport Delays Might Prevent You From Becoming the Next AirAsia 8501|Clive Irving|January 6, 2015|DAILY BEAST
He remembered something—the cherished pose of being a man plunged fathoms-deep in business.St. Martin's Summer|Rafael Sabatini
Hilda, trembling at the door, more than half expected Mr. Orgreave to say: "You mean, she's invited herself."Hilda Lessways|Arnold Bennett
He wanted to tell her that if she called her father, it would mean the end of everything for them, but he withheld this.The Homesteader|Oscar Micheaux
It was difficult, with the mean appliances of the time, to wring subsistence from the reluctant earth.The Unsolved Riddle of Social Justice|Stephen Leacock
With Bacon, experientia does not always mean observation; and may mean either experience or experiment.The Mediaeval Mind (Volume II of II)|Henry Osborn Taylor