isograph

[ahy-suh-graf, -grahf]

noun

(in the study of the geographical distribution of a dialect) a line drawn on a map to indicate areas having common linguistic characteristics.

Origin of isograph

First recorded in 1935–40; iso- + -graph

Related formsi·so·graph·ic

[ahy-suh-graf-ik] /ˌaɪ səˈgræf ɪk/, i·so·graph·i·cal, adjectivei·so·graph·i·cal·ly, adverb