careless

Not giving sufficient attention, thought, or effort to avoid errors, damage, or accidents.

• He lost his apartment keys again because of a careless mistake.

• Are drivers becoming more careless on icy roads during the winter?

Showing a casual lack of concern or effort, often appearing effortless or unstudied.

• She tossed her jacket onto the chair with a careless shrug.

• His careless grace on the dance floor immediately caught everyone's eye.