Which adjective refers to something that is smaller than most others of its type?

The adjective that refers to something that is smaller than most others of its type is "diminutive." This word specifically describes items or beings that are notably small in size relative to what is typical or expected. It often conveys a sense of endearment when referring to small creatures or objects, highlighting their petite stature.

In contrast, "poignant" relates to something that evokes a strong emotional response, particularly sadness or regret, and does not pertain to size. "Ameliorate" means to make something better or improve a condition, which does not address size at all. Lastly, "inexorable" refers to something that is relentless or unyielding, often in the context of a force or a process, but it also has no connection to physical size. Therefore, "diminutive" is clearly the appropriate choice in the context of denoting smaller-than-average size.