Synonyms for Ironwood (same or very similar meaning)
WordNet sense 1 (handsome East Indian evergreen tree often planted as an ornamental for its fragrant white flowers that yield a perfume; source of very heavy hardwood used for railroad ties):
rose chestnut, ironwood tree, Mesua ferrea
WordNet sense 2 (a small slow-growing deciduous tree of northern Iran having a low domed shape):
iron-tree, iron tree
WordNet sense 3 (medium-sized hop hornbeam of eastern North America):
Eastern hop hornbeam, Ostrya virginiana
From the ODE community, based on WordNet
add/edit