A more thorough explanation:

Definition: Countermand refers to a contradictory command that cancels or overrides a previous one. It can also refer to an action that nullifies something that was previously ordered or requested.

• After ordering the pizza, he countermanded his request and asked for a salad instead.
• The general countermanded the order to attack and instead ordered his troops to retreat.
• The CEO countermanded the decision to lay off employees after receiving backlash from the public.

These examples illustrate how countermand can be used to describe a situation where a previous order or decision is cancelled or changed. In the first example, the person changes their food order from pizza to salad. In the second example, the general changes the military strategy from attacking to retreating. In the third example, the CEO changes the decision to lay off employees after receiving negative feedback. In all cases, the original order or decision is countermanded and replaced with a new one.