Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Bitter orange
Bitter orange, Seville orange, sour orange, bigarade orange, or marmalade orange refers to a citrus tree (Citrus" × "aurantium) and its fruit. It is native to southeast Asia, and has been spread by humans to many parts of the world. Wild trees are found near small streams in generally secluded and wooded parts of Florida and The Bahamas after it was introduced to the area from Spain, where it had been introduced and cultivated heavily beginning in the 10th century by the Moors. The bitter orange is believed to be a cross between "Citrus maxima" × "Citrus reticulata"