IPA: /ˈmɑːstərlɪnəs/
KK: /ˈmæstərlɪnəs/
The quality of being very skilled or proficient in a particular area or activity.
Her masterliness in painting was evident in every brushstroke.
Masterliness → It is formed from "master" (from Old English "maegester", meaning one who has control or authority) and "-liness" (meaning the quality of being). The word "masterliness" refers to the quality of being a master or exhibiting mastery in a particular area.
Think of someone who has control or authority ('master') and the quality of that state ('-liness'). This helps you remember that 'masterliness' means the quality of being a master.