Webster's Revised Unabridged Dictionary · 1913

grapefruit

grapefruit (grāp"frot`) , noun

1.
A citrus tree (Citrus paradisi) bearing large round edible fruit having a thick yellow rind and juicy somewhat acid pulp.
2.
The large yellow fruit of the Citrus paradisi, having somewhat acid juicy pulp. It is a popular breakfast food.