Ma'anar ƙamus na kalmar "isochrone" wani lanƙwasa ne ko layi da ke haɗa dukkan maki da aka cim ma a lokaci guda, yawanci ta hanyar wani abu mai motsi kamar igiyar ruwa, sauti, ko barbashi. A wasu kalmomi, isochrone shine layin kwane-kwane wanda ke wakiltar daidai lokacin tafiya ko daidai lokacin isowa daga takamaiman wurin farawa. Ana amfani da kalmar sau da yawa a fannoni kamar tsarin sufuri, labarin kasa, da kimiyyar lissafi.