ˈ ̷ ̷ ̷ ̷ˌpleth noun
( -s )
Etymology: International Scientific Vocabulary is- + -pleth (from Greek plēthos quantity, multitude); akin to Greek plēthein to be full — more at full
1. : an isogram on a graph showing the occurrence or frequency of a phenomenon as a function of two variables — often used of meteorological elements
2. : a line on a map connecting points at which a given variable has a specified constant value
isopleths such as isothermal lines or topographic contour lines