'orexigenic' originates from Greek/Neo-Latin, specifically the Greek word 'orexis' (ὄρεξις), where 'orexis' meant 'appetite' and the combining element '-genic' comes from Greek 'genēs' meaning 'producing' or 'originating'.

'orexigenic' was coined in Neo-Latin/medical English by combining Greek roots 'orexis' + '-genic' (literally 'appetite-producing') and entered English usage in scientific and medical literature in the 20th century.

Initially it literally meant 'producing or causing appetite', and over time it has retained that technical meaning in pharmacology and physiology as 'stimulating appetite'.