n. 1 dominion, sway. 2 masterly skill. 3 (often foll. by of) comprehensive knowledge or use of a subject or instrument. 4 (prec. by the) the upper hand.
[ ME f. OF maistrie (as MASTER) ]
MASTERY
Meaning of MASTERY in English
Concise Oxford English dictionary. Краткий оксфордский словарь английского языка. 2012