野心 typically carries a negative connotation — overreaching or selfish ambition. For positive ambition, use 雄心 (xiōngxīn) or 抱负 (bàofù) instead. Common phrase: 野心勃勃 (wildly ambitious).
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A wild (野) heart (心) — ambition that is untamed and unchecked, like a beast that can't be controlled.
