hyssop

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

• noun A woody Eurasian plant (Hyssopus officinalis) in the mint family, having spikes of small blue or violet flowers and aromatic leaves used in perfumery, as a condiment, and formerly in medicine.
• noun Any of several similar or related plants, such as some species in the genus Agastache.
• noun An unidentified plant mentioned in the Bible as the source of twigs used for sprinkling in certain Hebraic purification rites.

from The Century Dictionary.

• noun A small bushy herb of the genus Hyssopus, natural order Labiateæ.
• noun In Scripture, a plant the twigs of which were used for sprinkling in the ceremony of purification.
• noun Eccles., same as aspersorium, See quotation from Preseott under aspersion, 1.
• noun In the western United States. sage-brush, Artemisia.

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

• noun A plant (Hyssopus officinalis). The leaves have an aromatic smell, and a warm, pungent taste.

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

• noun Any of several aromatic bushy herbs, of the genus Hyssopus, native to Southern Europe and once used medicinally
• noun Any of several similar plants
• noun obsolete, US The sage brush

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

• noun bitter leaves used sparingly in salads; dried flowers used in soups and tisanes
• noun a European mint with aromatic and pungent leaves used in perfumery and as a seasoning in cookery; often cultivated as a remedy for bruises; yields hyssop oil