in a way that is intentional or shows no care about bad things that might result

Their lives were brutally and wantonly cut short. 他们的生命被残酷而肆意地断送了。

I will not hesitate to identify countries which repeatedly and wantonly violate international law. 我将毫不犹豫地指出那些反复和肆意违反国际法的国家。

in a way that is, or appears to be, very sexual

She left her blonde hair wantonly loose around her face and shoulders. 她让自己的金发随意地散落在脸上和肩上。

She could not believe that she had behaved so wantonly. 她不敢相信自己的行为如此放纵。