What does Q mean in speaker specifications?

I have never seen that listed before on any speaker. Can you explain what the Q means on these Falcon speakers? THX



Falcon Acoustics is pleased to announce the re-introduction of the Falcon Acoustics Q7 “Complete@Home” Loudspeaker system. Designed by Malcolm Jones and sold by Falcon for many years, the updated Q7 features the same Falcon B110 and T27 drive units as used in the Falcon LS3/5a in a specially extended LS3/5a-type cabinet to produce an optimum Q=0.7 system with extra bass compared to the LSA3/5a (+2dB @ 50 Hz). Factory built options supplied built by Falcon, fully checked and tested are available.


I like the answers here. Very good. I'd like to add that in my DIY towers people are often amazed that I get so much bass from what appears to be 10-inch drivers, then I pull the grills off exposing only 8-inch drivers. This effect that everyone is talking about is simply utilizing the resonate freq of the enclosure to lift to the bottom end. If done well, you will not notice the rise but just experience a steady bass volume as the Frequency gets lower. And as one person mentioned what he called 'Stored' energy in the cabinet. Though this is a component it is ONLY a component. 

To be a little clear:

Qtc is a driver parameter.  You read it when shopping for a driver.

Total system Q is how a driver performs in a specific cabinet.  You adjust this when using a cabinet simulator.