What does the prefix cyano- mean?

The prefix cyano- means "blue". It is derived from the Greek word kyanos, which means "dark blue". The prefix cyano- is used in a variety of chemical and biological terms to indicate the presence of a cyano group, which is a carbon atom that is triple-bonded to a nitrogen atom. For example, the cyano group is found in the chemical compound hydrogen cyanide (HCN), which is a colorless gas that is highly toxic. The cyano group is also found in the biological compound cyanocobalamin, which is a form of vitamin B12.