Western Pennsylvania English, known more narrowly as Pittsburgh English or popularly by outsiders as Pittsburghese, is a dialect of American English native primarily to the western half of Pennsylvania, centered on the city of Pittsburgh, but potentially appearing as far north as Erie County, as far east as metropolitan State College, as far west as metropolitan Youngstown (Ohio), and as far south as micropolitan Clarksburg (West Virginia). Speakers with the strongest accent of this dialect, associated with the white working class of Pittsburgh, have been historically called Yinzers.
Scots-Irish, Pennsylvania German, and Slavic-speaking (especially Polish) immigrants to the area all provided certain loanwords to the dialect (see "Vocabulary" below). Although many of the sounds and words found in this dialect are popularly thought to be unique to the city of Pittsburgh only, this is a misconception, since the dialect resides throughout the greater part of western Pennsylvania and surrounding areas. Central Pennsylvania, currently an intersection of several dialect regions, was identified in 1949 by Hans Kurath as a sub-region between western and eastern Pennsylvania, though some scholars have more recently identified it within the western Pennsylvania dialect region. Since the time of Kurath's study, one of western Pennsylvania's defining features, the cot–caught merger, has expanded into central Pennsylvania, moving eastward until being blocked at Harrisburg. Perhaps the only feature whose distribution is restricted almost exclusively to the immediate vicinity of Pittsburgh is /aʊ/ monophthongization, in which words such as house, down, found, or sauerkraut are sometimes pronounced with an "ah" sound instead of the more standard pronunciation of "ow", rendering eye spellings such as hahs, dahn, fahnd, and sahrkraht.