Final answer:
Emotional stability/instability is the tendency to react to a situation in a stable way over time.
Step-by-step explanation:
Tendency to react to a situation in a way that remains stable over time is known as emotional stability/instability. Emotional stability refers to the degree to which a person's emotions remain stable and consistent, regardless of the situation. For example, a person with high emotional stability would react calmly and consistently to both positive and negative events.