Field-basil: A genus of the gymnospermia order, belonging to the didynamia clas of plants; and in the natural method ranking under the 4th order, Aperifoliæ. The involucrem consists of many small bristles under the verticillus or whirl of flowers. There are six species, all of them herbaceous plants, growing from one to two feet high. They are remarkable only for their strong odour, being somewhat between marjoram and basil.