Meaning

noun citrus tree bearing large round edible fruit having a thick yellow rind and juicy somewhat acid pulp

noun large yellow fruit with somewhat acid juicy pulp; usual serving consists of a half

originWidely assumed to be a marketing term from grape + fruit, an allusion to the supposed grapelike clusters of fruit on the tree, early 19th c. Ciardi proposes another theory: one of the pomelo's botanical names is Citrus grandis, meaning “great citrus [fruit]”, due to the size of its fruit. A new pomelo variety might first have been called a GRAYT-froot (see greatfruit), and through the process of…

Etymology from Wiktionary, CC BY-SA 3.0