'oblong-fruited' originates from Modern English, specifically formed by compounding 'oblong' (from Latin 'oblongus') and 'fruit' (from Old French 'fruit', from Latin 'fructus'), where 'oblongus' meant 'somewhat long' and 'fructus' meant 'produce' or 'enjoyment'.

'oblong-fruited' developed in Modern English by combining the adjective 'oblong' and the noun 'fruit' with the adjectival suffix '-ed'; 'oblong' entered English via Middle English/Old French from Latin 'oblongus', and 'fruit' entered via Old French from Latin 'fructus'.

Initially, 'oblong' meant 'somewhat long' and 'fruit' referred generally to produce; over time the compound 'oblong-fruited' came to specifically mean 'having oblong (elongated) fruits'.