bad boy; naughty child; brat
Refers to a mischievous or ill-behaved boy, often with a slightly old-fashioned or literary tone. Can be used affectionately or critically depending on context.
近所の悪童たちがまた塀を越えてきた。
The neighborhood brats climbed over the fence again.
彼は子供の頃、手のつけられない悪童だったらしい。
Apparently he was an uncontrollable bad boy when he was a child.
悪童 is a more literary or formal term for a mischievous boy, while 悪 in this sense is the everyday, often affectionate word for a naughty kid.
悪童 is a slightly literary, gentler word for a mischievous child, whereas ガキ is blunt, casual slang.
Compound of 悪 (aku, 'bad, evil') and 童 (dō, 'child, juvenile'). The reading is on'yomi, and the word has been used in literary Japanese to describe a mischievous or delinquent boy.