assertive (adj.)

• absolute
• affirmative
• affirmatory
• aggressive
• bold
• bossy
• certain
• confident
• decided
• declarative
• declaratory
• definite
• doctrinaire
• dogmatic
• domineering
• emphatic
• firm
• insistent
• opinionated
• peremptory
• positive
• predicative
• pushy
• sure