Definition
Used to suggest a stronger or more extreme description, while avoiding direct use of it for politeness or caution.
甚至，或者说
The plot of this movie is complex, not to say confusing.
这部电影的情节很复杂，甚至有点让人困惑。
His contribution to the project was minimal, not to say non-existent.
他对这个项目的贡献微乎其微，甚至可以说是不存在。
The project was delayed, not to say a complete failure.
这个项目被延迟了，甚至可以说是彻底失败。