The definition you gave seems to have the definitions for resonance and reverb built into one, which makes it more confusing.
From a physics perspective, everything has various resonant or natural frequencies. Here's a little tidbit if you're interested. These characteristics are known better to musicians as harmonics.
As I learned in physics:
Resonance occurs when a material/object is vibrated at its natural frequency.
This is a unique occurrence which causes something to vibrate. Something else (the origin of the sound) must have vibrated at this same frequency. From the above linked source:
The result of resonance is always a big vibration - that is, a loud sound.
Thus, resonance is a phenomenon which occurs due to the physical properties of a material. So, you could say that resonance emphasizes or reinforces a sound. One example is that buzzing/rattling which happens with loud bass.
Reverb is just what you think it is. It's just the "dying out" or extension of a sound. Like you said:
the...prolongation of sound by reflection from a surface...
Whereas resonance could be defined as
the reinforcement...of sound...by the synchronous vibration of a neighboring object
In the context of sound production, resonance causes certain frequencies to become more prominent in rooms which have those natural frequencies. A large room or hall, etc. will reverberate any sound, though, because the echoes take a long time to die off.
While mixing, the line definitely blurs. You can certainly emulate resonance with EQs and reverberation. And if you're not doing any recording, you really don't need to worry about the difference.