undiplomatic (adj.)

• airy
• brash
• careless
• casual
• cursory
• degage
• easygoing
• flippant
• forgetful
• heedless
• impolitic
• inconsiderate
• indifferent
• insouciant
• lazy
• maladroit
• oblivious
• offhand
• perfunctory
• reckless
• regardless
• tactless
• thoughtless
• unheeding
• unmindful
• unprepared
• unready
• untactful
• unthinking