The Collaborative International Dictionary of English v.0.48:
Adeptness \A*dept"ness\, n. The quality of being adept; skill. [1913 Webster]WordNet (r) 3.0 (2006):
adeptness n 1: skillful performance or ability without difficulty; "his quick adeptness was a product of good design"; "he was famous for his facility as an archer" [syn: adeptness, adroitness, deftness, facility, quickness]