or Colocynth. Bitterapple or colocynth. (Greek, kolokunthis.)
“The food that to him now is luscious as locusts, shall be to him shortly as bitter as coloquintida.” —Shakespeare: Othello, i. 3.
(St.). Charles I. was so called. He was bitter as gall to the Levellers.
“The Levellers styled him [Charles I.] an Ahab, and a Coloquintida, a man of blood, and the everlasting obstacle to peace and liberty.” —Howitt: History of England (“Charles I.,” chap. vi. p. 284).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894