Which of the following terms describes someone with a significant lack of emotion?

The term that accurately describes someone with a significant lack of emotion is "flat affect." This term is often used in psychological contexts to refer to a noticeable reduction in emotional expression. Individuals displaying flat affect may exhibit little to no facial expression, voice intonation, or other cues that typically convey feelings or emotional responses.

In contrast, emotional instability refers to unpredictable and extreme emotional responses, while hyper-empathy describes an excessive ability to understand and share the feelings of others, leading to heightened emotional reactivity. Emotional resilience denotes a person's capacity to adapt and recover from stress or adversity. Thus, flat affect specifically captures the absence of emotional expression, making it the correct choice.