Bitter Orange, also known as Seville Orange and Bigarade, is a sturdy, evergreen citrus species that is indigenous to India and is cultivated in Spain, Sicily, Morocco, the southern US and the Caribbean – diverse regions with similar climates. Citrus aurantium var. amara is a hybrid of Citrus maxima (pomelo) and Citrus reticulata (mandarin) and is the preferred fruit used for natural perfumery. Along with Neroli (Orange Blossom) and Petitgrain Bigarade (Orange Leaf) essential oils and absolutes, Bitter Orange has one of the three important aromas derived from Citrus aurantium var. amara.

Limonene is the primary constituent (up to 95%) in Citrus aurantium; along with other citrusy terpenes, esters, coumarins and oxides, it is responsible for the sparkling fresh, tart, fruity green aroma. As described by Steffen Arctander, its aroma is "fresh and yet 'bitter' in the sense of 'dry', but with a rich and lasting, sweet undertone… overall, the odor is distinctly different from that of other citrus oils. It is a different type of freshness, [with] a peculiar floral undertone…"[1] Natural perfumer Ayala Moriel appraises Bitter Orange oil as a flower’s best friend, having "…excellent uplifting qualities … [it] blends beautifully with florals, showcasing their beauty like no other citrus does." It may be for its distinctly different aroma that Bitter Orange seems to be preferred in many high-end perfumes.