Dialectology (from Greek διάλεκτος, dialektos, `talk, dialect`; and -λογία, -logia) is the scientific study of linguistic dialect, a sub-field of sociolinguistics. It studies variations in language based primarily on geographic distribution and their associated features. Dialectology treats such topics as divergence of two local di.....
study of dialects
• (n.) That branch of philology which is devoted to the consideration of dialects.
the study of dialects. Variation most commonly occurs as a result of relative geographic or social isolation and may affect vocabulary or features ... [1 related articles]
Di`a·lec·tol'o·gy noun [ Dialect + -logy .] That branch of philology which is devoted to the consideration of dialects. Beck. 
noun the branch of philology that is devoted to the study of dialects
the study dealing with dialects and dialect features. · the linguistic features of a dialect or of the dialects of a language.