1. co - Noun
2. co - Pronoun
3. Co - Proper noun
a hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition
an odorless very poisonous gas that is a product of incomplete combustion of carbon
a state in west central United States in the Rocky Mountains
one who refuses to serve in the armed forces on grounds of conscience
Source: WordNet