mas·ter·ful 
(măstər-fəl)
(măstər-fəl)adj.
1. Acting or capable of acting as a master or leader, especially in being domineering or imperious: "Do you agree with me that I have a right to be a little masterful, abrupt; perhaps exacting, sometimes" (Charlotte Brontë).
2. Having or showing mastery or skill; expert: a masterful technique; masterful at filmmaking.
master·ful·ly adv.
master·ful·ness n.
Usage Note: According to a widely repeated dictum, masterful should be reserved for the sense "imperious, domineering" (as in a masterful tone of voice), whereas masterly should be the choice when the intended sense is "having the skill of a master" (as in a masterly performance of the sonata). But in practice writers have been less heedful, and today masterful is well attested with the meaning "finely skilled." In fact, the word masterful is far more likely to occur before words like performance and ability than masterly is.