"With" or "Together"
* Combine: To join together.
* Communicate: To share information.
* Commemorate: To honor the memory of.
* Compete: To strive for the same goal.
* Compose: To create by combining parts.
* Compound: To combine or make more complex.
* Compromise: To reach an agreement by giving up something.
* Compute: To calculate.
* Concentrate: To focus attention.
* Concur: To agree.
* Cooperate: To work together.
"Completely" or "Thoroughly"
* Complete: To finish something.
* Comfortable: Providing a feeling of ease and relaxation.
* Commendable: Deserving praise.
* Commemorate: To remember something.
* Compel: To force or urge.
* Complain: To express dissatisfaction.
* Compliment: To praise.
* Compose: To write or create.
* Confident: Certain.
* Confirm: To make sure something is true.
Other Meanings
* Commerce: The exchange of goods and services.
* Command: To give an order.
* Commit: To promise or pledge.
* Common: Shared by many.
* Community: A group of people living in the same place.
* Commotion: A state of disturbance.
* Companion: Someone who accompanies another.
* Compare: To examine two things to find similarities and differences.
* Compass: A tool for navigation.
This is just a small sample of words that begin with "com". There are many more depending on the specific meaning you are looking for.