This word literally means "head" and was used to describe the highest point of a hill or mountain.
Other related words include:
* "heafodland": a piece of land on the top of a hill
* "heafodweard": a guardian or watchman at the top of a hill
While "heafod" is the most direct translation for "crest of a hill," it's important to remember that Old English had a rich vocabulary, and there might be other, less common words that could also be used.