WordNet sense 1 (a heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood):

Fe

WordNet sense 2 (implement used to brand live stock):

branding iron

WordNet sense 3 (home appliance consisting of a flat metal base that is heated and used to smooth cloth):

smoothing iron

WordNet sense 4 (extremely robust):

cast-iron

WordNet sense 5 (physically strong):

robust

WordNet sense 6 (press and smooth with a heated iron):

press, iron out