isochrone

[ ahy-suh-krohn ]
/ ˈaɪ səˌkroʊn /

noun

a line, as on a map, connecting all points having some property simultaneously, as in having the same delay in receiving a radio signal from a given source or requiring the same time to be reached by available transportation from a given center.

Origin of isochrone

1690–1700; back formation from isochronous or isochronal

British Dictionary definitions for isochrone

isochrone
/ (ˈaɪsəʊˌkrəʊn) /

noun

a line on a map or diagram connecting places from which it takes the same time to travel to a certain point