wickedness: active moral evil and the guilt it carries, the settled opposite of doing right
Rish'ah is the noun for wickedness: not one wrong act but the whole condition of being and doing evil, together with the guilt that clings to it. It is the fixed opposite of righteousness, and the two are repeatedly set side by side, one keeping a person safe and the other dragging him down.
A thread runs through these verses: wickedness recoils on the one who practices it. Proverbs says it overthrows the sinner and topples the wicked by their own weight. Isaiah pictures it as a fire that consumes, and Zechariah even personifies it as a figure sealed inside a basket and carried off. In the same vein the prophets speak of a nation's wickedness as the reason God acts against it, and of a person's wickedness as something charged to his own account, which he can also turn away from and be spared. Wickedness here is never neutral or self-contained; it is a debt that comes due.
In one legal setting the word narrows to the guilt itself: a guilty man is beaten in proportion to what he has done to deserve it. There the wickedness is measured and weighed against a penalty, closer to the English word "guilt" than to a broad "evil."
The closest relative is the masculine noun רֶשַׁע, which covers much the same ground; a separate word names the wicked person himself, while rish'ah is the wickedness he embodies.