This is the 686th most frequent Chinese word.
共产党员
Communist Party member.
Here, '共产党员' serves as a noun phrase referring to a specific role or identity, that of a member of the Communist Party.
他是一名忠诚的共产党员。
He is a loyal Communist Party member.
In this sentence, '共产党员' describes one's affiliation, setting the context for one's actions or responsibilities.
作为一个共产党员，他总是为人民服务。
As a Communist Party member, he always serves the people.
Here, '共产党员' is used to indicate a state or role that the speaker has considered or not considered adopting.