henna

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A tree or shrub (Lawsonia inermis) of the Middle East, having fragrant white or reddish flowers.
• noun A reddish-orange dyestuff prepared from the dried and ground leaves of this plant, used especially in South and Southwest Asia and North Africa to color leather and fabrics, to dye hair, and to decorate the skin.
• noun A design drawn on the skin with this dyestuff.
• noun A moderate or strong reddish brown to strong brown.
• transitive verb To dye (hair or skin, for example) with henna.

from The Century Dictionary.

• noun The Egyptian privet or flower of Paradise, Lawsonia inermis, of the natural order Lythrarieœ, a shrub bearing opposite entire leaves and numerous small and fragrant white flowers.
• noun A paste made from the leaves of this plant by mixture with catechu, used in the East by women to stain their nails, finger-tips, and eyelids. and by men to dye their beards.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A thorny tree or shrub of the genus Lawsonia (Lawsonia 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 nails and fingers, the manes of horses, etc.
• noun (Com.) The leaves of the henna plant, or a preparation or dyestuff made from them.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A shrub, Lawsonia inernis, having fragrant reddish flowers
• noun A reddish plant substance, prepared from the dried leaves of this plant, used for temporary tattoos and hair coloring. Hair colorings range from bright red to earth brown to near black.
• noun A rich reddish-brown colour.
• adjective Of a rich reddish-brown colour.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb apply henna to one's hair
• noun a reddish brown dye used especially on hair