What does suffix dean mean as in withdean?

The suffix "dean" in "Withdean" is not a stand-alone word with a meaning of its own. It's part of a larger place name and has its roots in Old English.

Here's a breakdown:

* With-: This element comes from Old English "wiþ", meaning "with" or "by".

* -dean: This element comes from Old English "denu", meaning "valley" or "ravine".

Therefore, "Withdean" literally means "by the valley". It's likely the name originated as a descriptor of the area's geography, referring to a valley near a particular location.