When we think of the word "underpowered", a sense of lacking strength or capability comes to mind. However, there are several synonyms that convey this concept with different nuances. "Weak" or "feeble" suggest a lack of vigor or forcefulness, while "ineffective" implies an inability to produce the desired result. "Inadequate" emphasizes insufficiency or a failure to meet expectations. "Underperforming" refers to a shortfall in meeting performance standards. Additionally, "powerless" denotes a complete absence of power, while "impotent" suggests a lack of potency or effectiveness. All these synonyms capture the essence of "underpowered" and can be used effectively to describe a range of situations or objects that lack the necessary strength or capacity.