What is the meaning of 肉桂?

cassia (the Chinese cinnamon Cinnamomum cassia)

cassia bark (herb used in traditional Chinese medicine for various ailments)

related members of the genus Cinnamomum, such as true cinnamon (C. verum), Indonesian cinnamon (Cinnamomum burmanni), and Vietnamese cinnamon (Cinnamomum loureiroi)

bark of such trees

Cinnamomum sieboldii, a species of cinnamon

cinnamon, a general term for trees of genus Cinnamomum

hanja form of 육계 (“Cinnamomum cassia”)

chữ Hán form of nhục quế (“Cinnamomum cassia”)

Source: wiktionary.org