Masterful, domineering, imperious, peremptory, imperative are comparable when they apply to persons or their acts, utterances, and demands and mean governed by, or manifesting, a strong tendency to impose one's will on another.
One is masterful who by the strength and virility of his personality is able to enforce his will on others or who deals with affairs commandingly and compellingly.
One is domineering who tries to enforce his will or to make a show of his power by an overbearing or insolently tyrannical manner.
One is imperious who by temperament or by position is fitted to command or who assumes the air or manner of such a person; the term implies more arrogance than masterful and less insolence than domineering.
One is peremptory who insists, often with curtness, on an immediate response to his commands; the term usually implies authoritativeness and a refusal to brook disobedience or delay or to entertain objections however valid.
One is imperative who, or whose behavior, is peremptory because of the urgency of the situation rather than because of a domineering temperament.