开 (kāi): While commonly meaning “to open,” in this context, it takes on the meaning of “to dismiss” or “to initiate an action against.” It's the same “kāi” as in `开会 (kāihuì)` (to start a meeting) or `开车 (kāichē)` (to drive a car), but here it's part of the set phrase `开除`.
除 (chú): This character means “to remove,” “to get rid of,” or “to eliminate.”
党 (dǎng): This means “political party.” In the vast majority of contexts in mainland China, it implicitly refers to the one and only ruling party: the Communist Party of China (中国共产党).
籍 (jí): This character refers to a register, a record of membership, or one's native place. Here, it means “membership” or “enrollment.”
When combined, `开除 (kāichú)` means “to expel.” `党籍 (dǎngjí)` means “Party membership.” Therefore, `开除党籍` literally translates to “to expel from the Party's membership register.”
In China, the Communist Party isn't just a political organization you join like the Democrats or Republicans in the US. It is a vast, hierarchical institution deeply intertwined with the government, the military, state-owned corporations, and even the social fabric of the nation. Party membership (being a `党员, dǎngyuán`) is a significant status symbol, often a prerequisite for advancement in many powerful and prestigious careers.
Therefore, being expelled from the Party (`开除党籍`) is a catastrophic event.
Comparison with Western Concepts: Comparing `开除党籍` to being “kicked out of a political party” in the West fails to capture its severity. A better, though still imperfect, analogy would be a combination of being disbarred as a lawyer, excommunicated from a powerful state church, and publicly shamed in a national headline—all at once. It signifies a complete severance from the power structure. The expulsion is a declaration that the individual is no longer considered part of the political elite and is now a pariah.
The Path to “Shuāngkāi” (Double Expulsion): This term is almost always seen alongside another action: `开除公职 (kāichú gōngzhí)`, meaning “to dismiss from public office.” When a corrupt official is punished, they are typically subjected to both. This is so common that it's abbreviated in news headlines and popular discussion as `双开 (shuāngkāi)` or “double expulsion.” Seeing `shuāngkāi` in a news report means an official's career is over, and a prison sentence is likely next.