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.
Meyer lemon
Citrus" × "meyeri, the Meyer lemon, is a hybrid citrus fruit native to China. It is a cross between a citron and a mandarin/pomelo hybrid distinct from the common or bitter oranges.