ˈ ̷ ̷ˌ ̷ ̷( ̷ ̷) noun
1. : an iron that has a flat smooth surface for ironing clothes and that typically has a base with the general contour of an isosceles triangle — compare box iron , sadiron
2. geology : a short triangular hogback that when viewed from the side resembles a huge flatiron standing on its heel
3. also flatiron collier Britain : a coal carrier with hinged funnels and masts used on the Thames river