Easton's Bible Dictionary (1897)
(1.) Hebrew kiddah’, i.e., “split.” One of the principal spices of the holy anointing oil (Ex. 30:24), and an article of commerce (Ezek. 27:19). It is the inner bark of a tree resembling the cinnamon (q.v.), the Cinnamomum cassia of botanists, and was probably imported from India. (2.) Hebrew pl. ketzi’oth (Ps. 45:8). Mentioned in connection with myrrh and aloes as being used to scent garments. It was probably prepared from the peeled
bark, as the Hebrew word suggests, of some kind of cinnamon.
Smith's Bible Dictionary (1863)
(Exodus 30:24; Ezekiel 27:19) The cassia bark of commerce is yielded by various kinds of Cinnamomum, which grow in different parts of India. The Hebrew word in (Psalms 45:8) is generally supposed to be another term for cassia.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
CAS'SIA . [scripture]Ex. 30:24[scripture]. The bark of a tree (Cinnamomum cassia) like the cinnamon, and one of the ingredients of the holy anointing oil. It was brought from India by the Tyrians. The Hebrew refers, in Ps 45:8, to another kind of spice, remarkable for its fragrance, and not yet identified with much probability.