Sentence:  He marched under a placard reading "End Bossiness Now" but decided it was a little too <WSD>peremptory</WSD>, not quite British, so changed the slogan on subsequent badges, to "End Bossiness Soon." 
Meaning of the word marked with <WSD> tags:  Positive in opinion or judgment; absolutely certain, overconfident, unwilling to hear any debate or argument (especially in a pejorative sense); dogmatic.