* Vocal: Relating to the voice or the act of speaking.
* Vociferous: Making a loud and forceful outcry.
* Vocation: A strong feeling of suitability for a particular career or occupation.
* Advocate: A person who publicly supports or recommends a particular cause or policy.
* Vocalist: A singer, especially one who performs solo.
* Vocabulary: The set of words used in a particular language or by a particular person or group of people.
* Vowel: A speech sound produced with the vocal cords vibrating, with no obstruction of the airflow in the mouth.
* Invoke: To call upon (a deity, spirit, or power) for assistance or protection.
* Evoke: To bring or recall (a feeling, memory, or image) to the mind.
* Revoke: To cancel or withdraw (a decision, law, or agreement).
These are just a few examples. There are many other words that use the prefix "voc," depending on the specific context.