affectatious
adjective
af·fec·ta·tious ˌa-ˌfek-ˈtā-shəs also -fik- 
: characterized or marked by affectation : affected
Do some people adopt an affectatious dialect to suit their audience? 
Pittsburgh Tribune Review, 12 Jan. 2010
Pittsburgh Tribune Review, 12 Jan. 2010
Word History
Etymology
affectati(on) + -ous
First Known Use
1676, in the meaning defined above