Overkill capability refers to an excessive amount of power or force utilized to achieve a desired outcome. When seeking alternative terms for this phrase, one could explore synonyms such as "excessive firepower," denoting an abundance of weaponry or strength deployed when it may not be necessary. Additionally, "disproportional capability" emphasizes the notion of an imbalanced level of power, highlighting the overwhelming force employed. Another possible synonym is "surplus strength," which implies an excess or surplus of power that surpasses the required amount. Ultimately, these synonyms help emphasize the notion of an excessive or overwhelming amount of force in relation to a particular objective.