Final answer:
Emotional instability in the Big Five personality model is termed neuroticism, one of the five factors which also include openness, conscientiousness, extraversion, and agreeableness.
Step-by-step explanation:
In the widely acknowledged Big Five personality model, emotional instability is referred to as neuroticism. Neuroticism is one of the five factors and is associated with the tendency to experience negative emotions such as anger, anxiety, and irritability. People high in neuroticism typically display higher levels of emotional instability and may react more negatively to stress. In contrast, those who score low on this trait tend to be calmer and more emotionally stable.
The Big Five personality factors, which can be remembered using the mnemonic OCEAN, include Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. These traits represent a range between two extremes and most people will fall somewhere in between these polarities. This model suggests that traits tend to be stable throughout the life span and are also believed to have a biological and genetic basis.