We don't have synonyms for iron oak yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are iron out, ironwork and iron man.
(n) :
medium-sized evergreen of southwestern united states and northwestern mexico with oblong leathery often spiny-edged leaves
(n) :
small deciduous tree of eastern and central united states having dark green lyrate pinnatifid leaves and tough moisture-resistant wood used especially for fence posts
(n) :
medium-sized evergreen of southwestern united states and northwestern mexico with oblong leathery often spiny-edged leaves
(n) :
small deciduous tree of eastern and central united states having dark green lyrate pinnatifid leaves and tough moisture-resistant wood used especially for fence posts