carelessly
Definitions
In a way that does not show enough attention or thought.
Without due concern or caution; heedlessly.
Examples
He carelessly left his keys on the roof of the car before driving away.
She carelessly dropped the fragile vase, causing it to shatter into pieces.
Synonyms
heedlessly recklessly negligently thoughtlessly inadvertently hastily slapdash
Antonyms
carefully cautiously meticulously attentively deliberately thoughtfully thoroughly