The word originated from busy-ness, the state of being busy.

The Oxford English Dictionary shows one commercial definition going back to 1727:
“Trade, commercial transactions or engagement.”

But the sense of “a commercial enterprise regarded as a ‘going concern’; a commercial establishment with all its ‘trade’, liabilities, etc.” is only traced back by the OED to the relatively modern 1888.

Although business historically has been distinguished from the government sector and the social/charity/not-for-profit sector, today writers about management will generally treat all organisations as having similar generic dimensions to their management, while recognising that there are still major cultural, political and stakeholder differences between the three broad sectors, and (of course) within each sector as well.