I think, I found it. I have a conspiracy theory 😉
In Russian, there is a word “Далеко” [Daleko], meaning “far away”.
So, the name of Daleks might come from the Russian word.
Actually, it sounds even more realistic, if we recall the year, when Daleks were introduced first – 1964.
Two years after Cuban missile crisis happened.
Similarity between Daleks and Soviet union from the point of view of that time Britain is very clear – total destroy of the world. The problem similar to Cuban crisis happened with Time Lords and Daleks. I always thought, that The Doctor looks like an american, who fall in love with Britain and stayed to live.
So, my conclusion is that Daleks symbolize Soviet Union.