any of various summer squashes, as the cocozelle and zucchini.
Origin
1810-20
British Dictionary definitions for vegetable marrow
vegetable marrow
noun
1.
a cucurbitaceous plant, Cucurbita pepo, probably native to America but widely cultivated for its oblong green striped fruit, which is eaten as a vegetable
2.
Also called (US) marrow squash. the fruit of this plant