Ladanum \Lad"a*num\, n. [L. ladanum, ledanum, Gr. la`danon, lh`danon, fr. lh^don name of a shrub, mastic; cf. Per. l[=a]dan, l[=a]den. Cf. Laudanum.]

A gum resin gathered from certain Oriental species of Cistus. It has a pungent odor and is chiefly used in making plasters, and for fumigation. [Written also labdanum.]

Source: Webster's Revised Unabridged Dictionary (1913)