野性(やせい)

やせい
noun
wild nature; untamed instincts
naturepersonality
1. wild nature; untamed instincts; wildness
The untamed, instinctive nature of an animal or person, as opposed to what has been domesticated or civilized. Often describes rough, raw energy in a person's character.
Even dogs retain some wild instincts.
You can feel a wild energy in the way he plays.
Living in the mountains, the wildness that had been dormant in me awoke.

Common collocations

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野生(やせい) has the same reading but means living or growing in the wild (野生(やせい)動物(どうぶつ), wild animals). 野性(やせい) is the wild nature or instinct itself. A wild animal is 野生(やせい)動物(どうぶつ); a rugged man is 野性的(やせいてき).