* Koch (masculine) - This is the most common word for a male chef.
* Köchin (feminine) - This is the word for a female chef.
* Koch/Köchin (neutral) - This is the neutral form of the word for a chef, regardless of gender.
* Kochen - This is the verb for "to cook".
So, if you're talking about the person who prepares food, you would use Koch, Köchin, or Koch/Köchin. If you're talking about the act of preparing food, you would use Kochen.