Well here's what Merriam Webster has to say: http://www.merriam-webster.com/dictionary/half-volley
Your definition of "half volley" is reasonable, but if most people who hear the term immediately think "short hop" it's going to require some additional explanation when used your way. So it might be better to stick to common usage.
Maybe worth noting that the two terms are used the same way in soccer-- volley means kicking the ball before ground contact, half-volley means kicking it on the short hop. In both cases they fundamentally refer to situations, not techniques (though the situations may call for particular techniques).
I guess soccer got its terminology from tennis?