It can be used as an adjective or a noun, depending on the context. For example:
* Le grec (the Greek) - referring to a person from Greece
* La langue grecque (the Greek language) - referring to the language
* Un restaurant grec (a Greek restaurant) - referring to a restaurant serving Greek cuisine
It is important to note that the pronunciation of "grec" is slightly different than the English word "Greek". The "c" is pronounced as a "k" sound, similar to the "c" in "cake".