A valley, especially in the form of a natural hollow, small and deep.
"The old sailor laughed and called her a delinquent, though he secretly admired how spirited the dell was in her defiance."
A young woman; a wench.
In plain English: A dell is a small, sheltered hollow or valley surrounded by hills or trees.
"We spent our picnic in the shady dell between the two hills."
Usage: The term "dell" has been archaic and offensive since the 16th century to mean a young woman or wench and should not be used in modern English. In contemporary usage, it exclusively refers to a small hollow or valley between hills.
A surname.
"My neighbor, Mr. Dell, waved at me as I walked past his house yesterday."
The word dell comes from the Old English term for a small dale. It traveled into modern English with this same meaning of a narrow valley or hollow between hills.