If you say that someone is reckless, you mean that they act in a way which shows that they do not care about danger or the effect their behaviour will have on other people.
Recklessness invites disaster.粗心大意招致灾难。He soon regretted his recklessness.他不久便后悔他的鲁莽。The lads’ energy pleased him but their recklessness worried him.小伙子们的劲头使他高兴,他们的冒失又使他担心。