“Why is there a thing called a grapefruit, when there’s a fruit called a grape?”

“Why is the grapefruit called a grapefruit? I mean, there is already a fruit called a grape. Doesn’t make a lick of sense” was asked on Twitter on April 28, 2009. “Why is it called a grapefruit when there’s already a fruit called a grape?” was asked on Twitter on February 6, 2012.
 
The answer is that the name “grapefruit” refers to the clusters of fruit on the tree—clusters that resemble grapes on a vine.
 
     
Wikipedia: Grapefruit
The grapefruit (Citrus × paradis) is a subtropical citrus tree known for its sour to semi-sweet, somewhat bitter fruit. Grapefruit is a hybrid originating in Barbados as an accidental cross between two introduced species, sweet orange (C. sinensis) and pomelo or shaddock (C. maxima), both of which were introduced from Asia in the seventeenth century. When found, it was named the “forbidden fruit”; and frequently, it has been misidentified with the pomelo.
 
The grapefruit’s name alludes to clusters of the fruit on the tree, which often appear similar to that of grapes.
 
Library of Congress—Everyday Mysteries
Question:
How did the grapefruit get its name? It doesn’t look like a grape.
Answer: 
It is believed that the name refers to the manner in which grapefruit grows in clusters on a tree.
     
Twitter
Jason Karsh‏
@jasonkarsh
Why is the grapefruit called a grapefruit? I mean, there is already a fruit called a grape. Doesn’t make a lick of sense.
1:08 PM - 28 Apr 2009
 
Twitter
Mr Ordinary ♒‏
@Robs_Wurld
#random ever wonder y a grapefruit is called a grapefruit when there is already a fruit called a grape
12:51 PM - 17 Apr 2010
 
Twitter
Bree.‏
@SweeeetBree
Why is it called a grapefruit when there’s already a fruit called a grape?
1:59 PM - 6 Feb 2012
 
Reddit—Shower Thoughts
Why is grapefruit called grape fruit when it neither looks like nor tastes like grape?
submitted October 27, 2014 by richyhuck
 
Reddit—Ask Reddit
Why is grapefruit called grapefruit when there’s already a fruit called grape?
(self.AskReddit)
submitted April 13, 2017 by smnmrk
COMMENTS
wetonred24
Why there watermelon when we already got water?
 
PirateKilt
The grapefruit was known as the shaddock or shattuck until the 19th century. Its current name alludes to clusters of the fruit on the tree, which often appear similar to grapes.
 
Reddit—Oneliners
Why is there a thing called a grapefruit, when there’s a fruit called a grape?
submitted October 27, 2017 by jewishing