desprateseagull said:'dean' could be an evolution of 'down', as in valley..?
Don't think they're connected but the Downs and dunes are derived from the same word (dun).
Combe or Coomb (as in Moulsecoomb) is also a valley, a word the Saxons borrowed from the Britons and which continues to be used in Welsh today (cwm).
What I'd like to know is this: if dean means valley, then why is Coldean built on a bleeding steep hill?