Ironwood is a common name for many woods or plants that have a reputation for hardness, or specifically a wood density that is heavier than water, although usage of the name ironwood in English may or may not indicate a tree that yields such heavy wood.

Lignum vitae is a wood, also called guayacan or guaiacum, and in parts of Europe known as Pockholz or pokhout, from trees of the genus Guaiacum. The trees are indigenous to the Caribbean and the northern coast of South America and have been an important export crop to Europe since the beginning of the 16th century. The wood was once very important for applications requiring a material with its extraordinary combination of strength, toughness, and density. It is also the national tree of the Bahamas, and the Jamaican national flower.