Webster’s Revised Unabridged Dictionary · 1913
Ladanum
Lad′a·num (lăd′ȧ·nŭm), n. [L. ladanum, ledanum, Gr. λάδανον, λήδανον, fr. λῆδον name of a shrub, mastic; cf. Per. lādan, lāden. 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.]