isoplethyoudaoicibaDictYouDict[isopleth 词源字典]
"A line on a map connecting points having equal incidence of a specified meteorological feature", Early 20th century: from Greek isoplēthēs 'equal in quantity', from Greek isos 'equal' + plēthos 'multitude, quantity'.[isopleth etymology, isopleth origin, 英语词源]