Answer is: covalent bond.
Covalent bond is bond between nonmetals. Carbon (C) and oxygen (O) are nonmetals.
Carbon atom and oxygen atom are connected by a triple bond (six shared electrons in three bonding molecular orbitals) that is formed of two covalent bonds and one dative covalent bond.
Dative covalent bond is formed by two electrons derive from the oxygen atom.
Carbon monoxide is a colorless, odorless, toxic and tasteless gas.