vehemently
Meaning: with intense force or emotion
Usage: The candidate vehemently opposed cutting back on Social Security funding.
imperious
Meaning: commanding, domineering
Usage: The imperious nature of your manner led me to dislike you at once.
peremptory
Meaning: insisting on immediate attention or obedience
Usage: The coach gave a peremptory order for everyone to leave the field.
domineering
Meaning: asserting control in an overbearing way
Usage: The domineering captain refused to let anyone else make suggestions.
authoritarian
Meaning: favoring strict obedience to authority
Usage: The authoritarian principal allowed no debate about the new rule.