So why chaos? Probably has something to do with the pseudo-random nature of hashing.
Chaos however is not random at all. It is completely deterministic. Chaos is when slight changes in initial conditions lead to big changes in final conditions. Of course big and slight are relative terms and accordingly chaos can only be relatively defined. But one thing it is not is stochastic.
So is hashing, that's why it's
pseudo-random. It's deterministic but any change in the input changes the output completely, in a way that to the unaided eye (and to any statistical test) seems random.
Saying that "chaos is completely deterministic" is meaningless. Chaos can exist in a theoretical deterministic system, but nature isn't deterministic, and chaos is what translates microscopic randomness to macroscopic randomness.
In fact chaos can be precisely defined, it's when the accuracy required in the initial conditions to obtain a given accuracy in the final conditions is exponential in the time span between the start and finish, as opposed to normal systems where it's polynomial.