offhanded

without previous thought or preparation

• “couldn”
• “;”
• “;”

in a casually inconsiderate manner

• “replied offhand, his mind a million miles away”
• “she threw him over offhandedly without even a Dear-John letter”

with little or no preparation or forethought

• “his ad-lib comments showed poor judgment”
• “an extemporaneous piano recital”
• “an extemporary lecture”
• “an extempore skit”
• “an impromptu speech”
• “offhand excuses”
• “trying to sound offhanded and reassuring”
• “an off-the-cuff toast”
• “a few unrehearsed comments”

casually thoughtless or inconsiderate

• “an offhand manner”
• “she treated most men with offhand contempt”