Noun

1. A person from the Republic of Congo.
2. A person from the Democratic Republic of Congo.

Usage notes

The term Congolese on its own is not strictly a nationality since it refers to two different nations, and it is therefore a regional or supranational word, like Dominican or Scandinavian. There is no simple modifier which can be added to the word to define which nation is meant. Sometimes the nation's acronym (ROC or DRC) is added before or after 'Congolese', as in 'DRC Congolese' or 'Congolese (DRC)', sometimes the names of the capitals are added:

Three of them were DRC Congolese and the other two were ROC Congolese

Three of them were (Kinshasa) Congolese and the other two were (Brazzaville) Congolese.

Adjective

1. Of, from, or pertaining to the Republic of Congo, its people or language.
2. Of, from, or pertaining to the Democratic Republic of Congo, its people or language.