Is there a word to describe when things are moving individually, but have a net velocity of zero? I know this is a strange question, but I know there must be a word for it.
So imagine a case where, taken as a whole, the net velocity of all particles equals zero, but each individual particle is moving. Here is what I am picturing:

For root words, I tried quasistatic, but it doesn't seem to have the same meaning since it is emphasizing the stability rather than the movement. I have thought of metastatic, using *meta- meaning change and *sta- which has the same root in stasis, but that one has the unfortunate connotation of cancer. As you can see, I am not at all well versed in linguistics or etymology, so help would be much appreciated.
 A: It might be described as pedesis or as random motion.
The picture shows the velocities of many particles (as in a gas the molecules all move around). Velocity is a vector: it has a speed and it has direction. In 3 dimensions this means that it has three components mutually at right angles: for present convenience, call them up/down, left/right, towards/away.
The net velocity in this case is the average velocity of all particles. To say it is zero is to say that the averages of each component of the vectors is zero. There is as much motion left as right, up as down, towards as away.

vector = a representation of something that has both direction and size
Cambridge

Note that the average velocity is zero although the average speed is not. The particles are all bouncing around in the box with various speeds but as a group they are going nowhere, so the average velocity is zero.
The group of particles is showing "random motion".
Brownian motion, or pedesis (from Ancient Greek: πήδησις /pɛ̌ːdɛːsis/ "leaping"), is the random motion of particles suspended in a medium (a liquid or a gas).
Wikipedia
