'peninsular' originates from Latin (via Late Latin), specifically the noun 'paeninsula' (from 'paene' + 'insula'), where 'paene' meant 'almost' and 'insula' meant 'island'.

'peninsular' was formed in English from the noun 'peninsula' (from Late Latin 'paeninsula') with the adjectival suffix '-ar' (from Latin '-aris'), producing 'peninsular' meaning 'of a peninsula'.

Initially associated with the idea of 'almost an island' (from 'paene' + 'insula'), it has come to mean simply 'relating to or characteristic of a peninsula' and also denotes a person from a peninsula.