The Collaborative International Dictionary of English v.0.48:

Olibanum \O*lib"a*num\, n. [LL., fr. Ar. al-luban frankincense;
   cf. Gr. ?, ?, of Semitic origin.]
   The fragrant gum resin of various species of Boswellia;
   Oriental frankincense.
   [1913 Webster]

WordNet (r) 3.0 (2006):

olibanum
    n 1: an aromatic gum resin obtained from various Arabian or East
         African trees; formerly valued for worship and for
         embalming and fumigation [syn: frankincense, olibanum,
         gum olibanum, thus]