So it would seem that this is where an accurate description of what is going on is necessary i.e. the correct term at the correct time, because of different actions within the process.
When a batch has started fermenting, a stirring or shaking action is usually described as "aeration", because the point of it at this point is to try and get some air/O2 into the batch to help with yeast development.
It's generally carried out until the batch hits the 1/3rd sugar break i.e. SG minus 1/3rd. Then the batch is usually just airlocked off to allow it to progress into the anaerobic phase of fermentation. It's also the point where the last of any intended nutrients is added.
A side effect of stirring for this reason, is that it moves any sediment about which creates the nucleation points for the dissolved CO2 a.k.a. carbonic acid, to attach to the the nucleation points when then collect the carbonic acid and forms bubbles of gaseous CO2 which rise out. This is quite a quick reaction and can form a foaming layer until the movement of the bubbles settles a bit or even reduces down. Of course, how much air/O2 that might get into the batch is dependent on the type of fermenter. CO2 is a "heavier than air" gas, so unless you've got a way of making sure that air/O2 is definitely getting in (pump or something like that), the effect of the stirring will mainly just remove dissolved CO2 as even when any bubbling/foaming has subsided, there'd still be a layer of it on top of the liquid surface. Some people like to use an airstone and either an aquarium pump or even compressed O2.
It's also the reason why, if you're doing staggered nutrient additions, that you'd stir first. To aerate, but also to get some of the gas out of solution so that when you add any granular/powdered material, it doesn't create the nucleation points and cause a foam eruption (which would be worse with a carboy/demi-john type fermenter as the neck of the bottle/jug creates a "jet").
Either way, any "normal" bubbling from an airlock will reduce due to the reduction in partial pressures from the escaping CO2 in the liquid. As the ferment progresses it will usually build back up again, though possibly to a lower level - which is why bubble rate/airlock activity is a very poor way of judging the state of the fermentation.
Your reliable method would be hydrometer readings (even refractometer readings aren't reliable as the presence of alcohol will throw off the refractive index that it measures - any readings would need to be compensated for to get close).
If you are just stirring to keep the sediment, whether it's live yeast or dead or just other particulates i.e. nutrients etc, you'd just stir gently, but even that could have a similar effect and depending on how much dissolved CO2/carbonic acid is still in the ferment, cause an eruption.
Now this kind of action might be described as "de-gassing" when it's done purely to remove dissolved CO2 after the end of the ferment. The only reason for it is to remove the gas. Which can be done in a couple of ways i.e. a "lees stirrer" or wine whip type stirring attachment. By hand or with it in a drill. Also by stoppering the fermenter and agitating it by shaking or rolling, then releasing the gas and doing this action again, until all the gas seems to have been agitated out of the liquid.
You can also, if the container can take it, use vacuum. With a "proper" vacuum pump, but care must be taken not to use too higher level of vacuum. With a "mityvac" type hand vacuum pump, which can take longer but is rather more controllable. You can even leave the degassing until the brew is cleared and in bottles with a "vacuvin" type pump, where you put the vacuvin stopper on the opened bottle, then apply the pump by hand, and keep doing that until the bubbles stop coming out of the liquid.
The other method that works well is vacuum racking, where you use a 2 holed bung on the carboy/demi-john that will receive the racked liquid. One hole in the bung is connected to a vacuum pump and the second hole in the bung to tubing and racking cane. The vacuum pump can be started and when it builds up enough vacuum in the empty vessel it will pull the liquid up the racking cane/tubing and you can then adjust the height of the racking cane down as the liquid level in the vessel with the liquid drops.
Direct vacuum will remove the most amount of carbonic acid, but obviously you have to be careful with the level of vacuum as glass is strong, but not that strong and you don't want to implode the vessel.
So you can see that using the correct term at the correct time helps others understand what it is that you're doing and at which stage in the making process.
Ok, I'll go and stand back in the corner now........
