noun
Casual, often rough-sounding term for a man; can be friendly or mildly dismissive depending on tone and context. Frequently used in male speech.
あの野郎、また遅刻かよ。
That guy is late again.
おい、野郎ども、飲みに行くぞ！
Hey, you guys, let's go drinking!
noun, pronoun
bastard; asshole; son of a bitch
Strongly derogatory and vulgar; used as an insult or angry exclamation, primarily by men. Often directed at someone the speaker is angry with.
この野郎、ぶっ飛ばしてやる！
You bastard, I'll knock you out!
あの野郎に騙された。
That son of a bitch tricked me.
Originally a compound of 野 (の, 'field, wild') and 郎 (ろう, 'young man, son'), suggesting a rough or uncouth man. The exact historical derivation is uncertain, but the term has long been used in colloquial Japanese with a derogatory edge.