Cassia typically refers to cassia bark, the spice made from the bark of East Asian evergreen trees.
Cassia may also refer to:
- Cinnamon trees
- Cinnamomum cassia (肉桂, ròuguì), the cassia or Chinese cinnamon, found in southern China and Indochina
- Other East Asian species of Cinnamomum, such as C. burmannii (Indonesian cinnamon) and C. loureiroi (the Vietnamese cinnamon)
- Osmanthus fragrans (桂花, guìhuā), is the osmanthus or sweet olive found in southern China and Indochina. References to the osmanthus in Chinese literature and poetry are often translated as "cassia" because both trees were formerly known in China as 桂 (Modern Standard Mandarin: guì). Similarly, "cassia" wine typically refers to Chinese wine flavored with osmanthus, not cassia proper.
- Cassia (genus), a genus of shrubs in the bean family Fabaceae
- Senna (plant), a genus of the bean family Fabaceae including species formerly treated in the genus Cassia:
- Acacia farnesiana, another member of Fabaceae
- Cassia gum, a food additive made from the seeds of Senna obtusifolia
- Cassia tea or senna tea, an herbal tea made from the seeds of Senna obtusifolia
- Cássia, a city in Minas Gerais, Brazil
- Cassia County, Idaho
- Cassia Creek, in the Mining regions of Idaho
- Via Cassia, a Roman road
- Cassia flask, a laboratory flask