nouveau riche

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who has recently become rich, especially one who flaunts newly acquired wealth.

from The Century Dictionary.

• One who has recently acquired wealth; one newly enriched; hence, a wealthy upstart; a parvenu.

from the GNU version of the Collaborative International Dictionary of English.

• A person newly rich. Contrasted with old money.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun pejorative New money; wealthy persons whose fortunes are newly acquired, and who are therefore perceived to lack the refinement of those who were raised wealthy.
• adjective Newly rich; like a nouveau riche.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective characteristic of someone who has risen economically or socially but lacks the social skills appropriate for this new position
• noun a person who has suddenly risen to a higher economic status but has not gained social acceptance of others in that class