Cinnamomum zeylanicum L. aka Laurus cinnamomum, Cinnamomum verum, Ceylon cinnamon. Steam distilled from the bark in Sri Lanka (formerly called Ceylon).

Aroma: A strong aromatic middle to base note, characteristic of its sweet-spicy warm tenacious odour -peppery, earthy, spicy, bright yet slightly woodsy.

Cinnamomum zeylanicum originates in Sri Lanka. It is a tropical evergreen tree of the laurel family growing up to 15 m (45 feet) in the wild. The tree has a very thin smooth bark, with a light yellowish-brown colour and a highly fragrant odour. Its pleasant scent makes it, in small amounts, spicy addition to creams, lotions, and soaps.

Common Uses: sluggish digestion, colds/flu, exhaustion, lice, circulation, rheumatism, scabies, stress
Source: Julia Lawless, The Encyclopedia of Essential Oils (Updated Edition) (London: Harper Thorsons, 2014), 74-75.

Main Constituents:
(E)-Cinnamaldehyde: 67 - 75%
Eugenol
(E)-Cinnamyl Acetate
Linalool
B-Caryophyllene
p-Cymene
See Essential Oil Safety for a more complete list of typical constituents.
Source: B.M. Lawrence, Essential Oils 1988-1991 (Wheaton: Allured Publishing, 1995), 201. F. Tateo, F. Chizzini, The Composition and Quality of Supercritical CO2 Extracted Cinnamon. (Journal of Essential Oil Research 1, 1989), 165-168. K.H. Kubeczka, Essential Oils Analysis by Capillary Gas Chromatography and Carbon-13 NMR Spectoroscopy, Second Edition. (Chichester: Wiley, 2002). Sources cited in Robert Tisserand and Rodney Young, Essential Oil Safety (Second Edition. United Kingdom: Churchill Livingstone Elsevier, 2014), 248-249.

Description / Colour / Consistency: A thin, yellow to amber clear liquid.

Blends With: Clove Bud, Frankincense, Nutmeg, Orange Sweet, and other Spice Essential Oils and can give depth to floral blends, especially Ylang-ylang.

Cautions: There is a high risk of skin sensitization with the bark oil, and Tisserand and Young recommend a dermal maximum of 0.07% for the bark oil. Tisserand and Young indicate that both the bark and the leaf oil are low risk for mucous membrane irritation, may inhibit blood clotting and pose a drug interaction hazard. Cinnamon Bark Oil may cause embryotoxicity and is contraindicated in pregnancy and breastfeeding. Reading Tisserand and Young's full profile for both the bark and leaf oils is recommended. [Robert Tisserand and Rodney Young, Essential Oil Safety (Second Edition. United Kingdom: Churchill Livingstone Elsevier, 2014), 248-250.]

This essential oil poses a higher risk of causing irritation and sensitization when used in the bath. Avoid using it in the bath, even if it is solubilized/diluted.

Photo thanks to By Simon A. Eugster - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=39582136