masterly

From Middle English maisterly, equivalent to master +‎ -ly.

• (UK) IPA^(key): /ˈmɑːstəli/

masterly (comparative more masterly, superlative most masterly)

1. Executed in the manner of a master; showing skill and competence.

   Her years of experience enabled her to render a masterly performance.

2. Imperious; domineering; arbitrary.

• masterly inactivity

masterly (comparative more masterly, superlative most masterly)

1. In a masterful manner; competently.
   • 1818, Belle Assemblée: Or, Court and Fashionable Magazine

     At length the sound of a flute broke upon mine ear; it was not played masterly, but the tones were very sweet; and what is more correct, perhaps, they harmonized with my feelings.

• “masterly” (US) / “masterly” (UK) in Oxford Dictionaries, Oxford University Press.