|Noah Webster's Dictionary|
1. (n.) A thorny tree or shrub of the genus Lawsonia (L. alba). The fragrant white blossoms are used by the Buddhists in religious ceremonies. The powdered leaves furnish a red coloring matter used in the East to stain the hails and fingers, the manes of horses, etc.
2. (n.) The leaves of the henna plant, or a preparation or dyestuff made from them.
Int. Standard Bible Encyclopedia
hen'-a (Songs 1:14; Songs 4:13): An aromatic plant.
Henna (2 Occurrences)
Song of Songs 1:14 My beloved is to me a cluster of henna blossoms from the vineyards of En Gedi. (WEB JPS ASV DBY NAS RSV NIV)
Song of Songs 4:13 Your shoots are an orchard of pomegranates, with precious fruits: henna with spikenard plants, (WEB JPS ASV BBE DBY NAS RSV NIV)