In my studies at the technical university in Delft, the following definition of geodesy was given:

is the science that deals with the determination of place, size and shape of the earth and parts thereof relative to other systems. (my translation from the Dutch in my textbook)

This definition is a little broader than the one given by Webster, and adds two elements I value:

  • it explicitly doesn't limit the scope of geodesy to earth itself
  • it points out that any result is relative to some chosen reference