The Collaborative International Dictionary of English v.0.48:

Dictamnus \Dic*tam"nus\ (d[i^]k*t[a^]m"n[u^]s), n. [L. See
   Dittany.] (Bot.)
   A suffrutescent herb, Dictamnus Fraxinella (the only
   species), with strong perfume and showy flowers. The volatile
   oil of the leaves is highly inflammable.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dittany \Dit"ta*ny\, n. [OE. dytane, detane, dytan, OF. ditain,
   F. dictame, L. dictamnum, fr. Gr. di`ktamnon, di`ktamnos, a
   plant growing in abundance on Mount Dicte in Crete. Cf.
   Dittander.] (Bot.)
   (a) A plant of the Mint family (Origanum Dictamnus), a
       native of Crete.
   (b) The Dictamnus Fraxinella. See Dictamnus.
   (c) In America, the Cunila Mariana, a fragrant herb of the
       Mint family.
       [1913 Webster]