Notwithstanding is mainly a preposition meaning in spite of. Most dictionaries also list it as an adverb meaning nevertheless, but this sense is rarely used in modern English. Notwithstanding is always one word, and this has been the standard spelling for many centuries.
Although notwithstanding usually means exactly the same as in spite of, it is often positioned differently. In spite of always comes before its object—e.g., “In spite of your feedback, I’m not changing anything.” But notwithstanding is often postpositive, meaning it comes after its object—e.g., “Your feedback notwithstanding, I’m not changing anything.” Of course, it can come before its object as well—e.g., “Notwithstanding your feedback, I’m not changing anything.”
Notwithstanding layoffs and cutbacks in the broadcast news business, CBS News writers are getting a slight bump in pay. [Los Angeles Times]
Provocation notwithstanding, the death toll at South Africa’s Marikana mine was the result of an outrageous, disproportionate overreaction by the police. [Irish Times]
Connoisseurship, notwithstanding the chemicals and gizmos modern science has concocted to aid in its detective work, remains an art. [NY Times]
Australia’s economy remains sound notwithstanding falling commodity prices and a slowdown in China. [Sydney Morning Herald]
The upbeat assessments of General David Petraeus notwithstanding, neither Karzai nor the Pakistanis believe the U.S. can win the war in Afghanistan. [Time]