grapefruit

[greyp-froot] /ˈgreɪpˌfrut/
noun
1.
a large, roundish, yellow-skinned, edible citrus fruit having a juicy, acid pulp.
2.
the tropical or semitropical tree, Citrus paradisi, yielding this fruit.
Origin
1805-15; grape + fruit, apparently from the resemblance of its clusters to those of grapes
British Dictionary definitions for grapefruit

grapefruit

/ˈɡreɪpˌfruːt/
noun (pl) -fruit, -fruits
1.
a tropical or subtropical cultivated evergreen rutaceous tree, Citrus paradisi
2.
the large round edible fruit of this tree, which has yellow rind and juicy slightly bitter pulp
Word Origin and History for grapefruit
n.

1814, from grape + fruit. So called because it grows in clusters. The fruit itself was known since 1693 (in Hans Sloane's catalogue of Jamaican plants); presumably it originated there from chance hybrids between other cultivated citrus. It was known by various names before the current one emerged. An ornamental plant chiefly at first, not much eaten until late 19c.