Cinnamon; also a variant of Cassia
Casia is a rare botanical name derived from the cassia plant, which produces a spice similar to cinnamon. It is often used as a simplified spelling of the Latin name Cassia, which has roots in the Roman family name Cassius. In some contexts, it is also associated with the Greek word for 'pure'.
Less common today
Casia isn't in the latest US Top 1000. It last peaked at #7,075 in 1999.
US births per 5-year period, 1990βpresent (SSA data).