isallobarPronunciation: /ʌɪˈsalə(ʊ)bɑː/Definition of isallobar noun Meteorology a line on a map connecting points at which the barometric pressure has changed by an equal amount during a specified time. Derivatives isallobaric adjective Origin: early 20th century: from iso- 'equal' + allo- 'other' + bar2isallobar in other Oxford dictionaries Definition of isallobar in the US English dictionary