isoglossn.

1925 O. Jespersen Mankind, Nation & Individual iii. 41 As a rule we find that the frontiers for one phenomenon do not exactly coincide with the frontiers for another, so that the ‘isoglosses’ (as such frontiers of single phenomena are called) sometimes agree, sometimes run somewhat parallel with one another, but fairly often cross one another in the most distracting manner.

1933 L. Bloomfield Lang. iii. 51 Within a dialect area, we can draw lines between places which differ as to any feature of language. Such lines are called isoglosses.

1949 H. Kurath Word Geogr. Eastern U.S. 11 In figure 2 the focus of each of the more distinctive sub-areas of the Eastern States is set off by a single word line or isogloss.

1953 J. B. Carroll Study of Lang. ii. 59 The purpose of linguistic geography is to make a detailed analysis of local linguistic variations... Efforts are made to establish isoglosses, which may be described as cartographic lines separating the geographical localities which show a difference with respect to a specific linguistic item.

1955 Publ. Amer. Dial. Soc. No. 23. 40 When it [sc. a form] is found within a sharply defined area, one may draw a line called an isogloss, to indicate the boundaries of the area in which this form occurs.

1958 Publ. Amer. Dialect Soc. xxx. 3 But a number of lexical terms do not occur in geographical patterns corresponding to the isogloss divisions for known Northern and Midland features.

1964 H. B. Allen in A. A. Marckwardt Stud. Lang. & Ling. in Honor C.C. Fries 305 The major isogloss bundle is shown on the map by the 1–1 line.

1968 Amer. Speech 43 185 It is separated from other dialects of Yiddish by a bundle of grammatical, phonological, and lexical isoglosses.

1968 W. S. Allen Vox Graeca i. 12 The ττ of pure Attic is part of an isogloss having its probable point of origin in Boeotian.

1932 Missouri Alumnus Apr. 232/1 The American Council of Learned Societies is financing a ‘Dialect Atlas of the United States and Canada’, and already the workers are making a survey of New England. They have a ‘work-sheet’ of 800 questions which bring to light the notable speech variations, and from the information so gathered they construct maps with ‘iso-glottal’ lines like those on a topographic map.

1939 L. H. Gray Found. Lang. ii. 26 Such lines are termed isoglottic lines or isographs.

1954 Word 10 375 The location of different isoglottic lines did not coincide in one linguistic area.

1927 L. Bloomfield in Mod. Philol. Nov. 220 The boundaries of successive linguistic changes (isogloss lines) do not coincide... Isoglosses may be bundled along barriers to communication; if the barrier (e.g., a political boundary) is removed, the isoglossic bundle may be overlaid by later linguistic development.

1972 H. Kurath Stud. Area Ling. 60 The location of some representative isoglossic lines..is shown in Figure 21.