What term denotes having or showing little or no emotion?

The term that best describes having or showing little or no emotion is associated with being "apathetically." This means that a person displays a lack of interest, enthusiasm, or concern, making it a fitting choice when discussing emotional detachment or absence of feelings. Such a demeanor typically reflects indifference, where emotions that are commonly expressed in various situations are notably missing or suppressed.

In contrast, the other options present different emotional states. "Ebullient" refers to being cheerful and full of energy, which is the opposite of showing little or no emotion. "Lethargic" describes a state of sluggishness or lack of energy, which might involve decreased emotional expression but does not specifically denote a lack of emotion itself. "Flippant" indicates a lack of seriousness or a casual attitude, often in response to situations that might warrant a more serious or emotional reaction. Therefore, "apathetically" is the most accurate term for indicating little or no emotion.