The Collaborative International Dictionary of English v.0.48:
Impuissance \Im*pu"is*sance\, n. [Cf. F. impuissance.] Lack of power; inability. --Bacon. [1913 Webster] Their own impuissance and weakness. --Holland. [1913 Webster]WordNet (r) 3.0 (2006):
impuissance n 1: powerlessness revealed by an inability to act; "in spite of their weakness the group remains active" [syn: helplessness, weakness, impuissance]