Every term is defined twice: once the way a filing would put it, and once the way somebody would explain it to you across a table. The second one is usually the one that sticks.
Showing 2 terms
A price series generated purely by chance, in which each step is independent of the ones before it.
Plot 250 coin flips and you get trends, levels, breakouts and a passable head and shoulders. Chart readers cannot reliably tell one from a real series — which is why "it looks like a clean setup" is not evidence.
The measured variance of an n-period move divided by n times the variance of a one-period move.
A direct test of the square-root-of-time assumption. Above one and moves have been reinforcing each other; below one and they have been cancelling out; at one the series behaves like a random walk over that horizon.