The Collaborative International Dictionary of English v.0.48:
Ambidextrousness \Am`bi*dex"trous*ness\, n. The quality of being ambidextrous; ambidexterity. [1913 Webster]WordNet (r) 3.0 (2006):
ambidextrousness n 1: the property of being equally skillful with each hand [syn: ambidexterity, ambidextrousness]