parvenu

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

• noun A person who has suddenly risen to a higher social and economic class and has not yet gained social acceptance by others in that class.

from The Century Dictionary.

• noun One newly risen into notice, especially by an accident of fortune and beyond his birth or apparent deserts, whether as a claimant for a place in society or as occupying a position of authority; an upstart.
• Like or characteristic of a parvenu or upstart.

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

• noun An upstart; a man newly risen into notice.

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

• noun A person who has risen, climbed up, or has been promoted to a higher social class, especially through acquisition of wealth, rights, or political authority but has not gained social acceptance by those within that new class.
• adjective this sense?) Being a parvenu; also, like or having the characteristics of a parvenu.

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

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