Acetonitrile is an organic compound with the formula CH3CN. It is a colorless liquid that is used as a solvent and in the production of various chemicals. Acetonitrile is weakly basic and polar, and it has a unique smell that is often described as unpleasant or sweet.

Acetonitrile is not considered to be a medication or a drug, so it does not have a medical definition. However, it is sometimes used in the medical field as a solvent for various applications, such as in the preparation of pharmaceutical products or in laboratory research. It is important to handle acetonitrile with care, as it can be harmful if swallowed, inhaled, or contacted with the skin.