Chemistry. Chemical element with the symbol Fe. The metallic element is an essential trace element. Iron is an important constituent of proteins such as hemoglobin, myoglobin, cytochrome. It is involved in transport of oxygen as well as in the transport of electrons in photosynthesis and the respiratory chain, and in cellular oxidation mechanisms.
Adjective: ferrous (especially in the bivalent state) and ferric (especially in the trivalent state)