Illustrated Glossary of Organic Chemistry

Alkoxide (alkoxide ion; RO-): An ion with a negative formal charge on oxygen atom bonded to an sp3 carbon atom (often, but not always, part of an alkyl group). The conjugate base of an alcohol.

  
CH3CH2O-   
Methoxide ion, the
conjugate base of methanol.

Ethoxide ion, the
conjugate base of ethanol.

Tert-butoxide ion, the
conjugate base of tert-butanol.