A chunk is a
piece of
something. For
instance, to
blow chunks means to
expel pieces of
partially digested food from one's mouth.
Bigger than a chip (as in chip off the old block), but smaller than the biggest thing in existance. A chunk can be any portion of something, as long as it's smaller than the original.
eg. A chunk of that there mountain
This meaning is not related to chunky. Chunky would be used for something like she's kinda chunky