isoclinalPronunciation: /ˌʌɪsə(ʊ)ˈklʌɪn(ə)l/Definition of isoclinal adjective Geology denoting a fold in which the two limbs are parallel. Origin: mid 19th century (denoting 'equal magnetic inclination'): from iso- 'equal' + Greek klinein 'to lean, slope' + -alisoclinal in other Oxford dictionaries Definition of isoclinal in the US English dictionary