Origin of dialectal
In linguistics dialectal, not dialectical, is the term more commonly used to denote regional or social language variation: Dialectal variation is more marked in the South than elsewhere in the United States. In general writing either term may be found.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for dialectal
As to dialectal idioms or lingual peculiarities, I had not, of course, the most remote idea.The Round Towers of Ireland
But, as a matter of fact, nearly all our chief writers have recognised the value of dialectal words.
In this long list, filling 80 columns, the dialectal words are marked with a dagger .
They must certainly have been looked upon, at the first, as being rustic or dialectal.
The word is a compound of inter, between, and lope, a dialectal variant of “leap.”
Word Origin and History for dialectal
Online Etymology Dictionary, © 2010 Douglas Harper