The Collaborative International Dictionary of English v.0.48:
forcefulness \forcefulness\ n. physical energy or intensity. Syn: force, strength. [WordNet 1.5]WordNet (r) 3.0 (2006):
forcefulness n 1: physical energy or intensity; "he hit with all the force he could muster"; "it was destroyed by the strength of the gale"; "a government has not the vitality and forcefulness of a living man" [syn: force, forcefulness, strength]