Here are some possibilities:
* "Co-": This is a prefix meaning "with," "together," or "jointly." Examples include "cooperate" and "coexist."
* "Coc-": This is a prefix that is sometimes used in scientific names of animals and plants, usually relating to coccids, a group of insects.
* "Cook-": This is a word referring to the act of preparing food with heat.
If you provide more context, such as the word you are trying to understand, I may be able to help you further.