1.
natural enemy; natural predator
An animal that naturally preys on or threatens another species in the wild.
猫は鼠の天敵だ。
Cats are the natural enemy of mice.
この害虫には天敵がいないため、被害が広がっている。
Because this pest has no natural enemies, the damage is spreading.
農薬の代わりに天敵を利用した害虫駆除が注目されている。
Pest control using natural enemies instead of pesticides is attracting attention.
2.
nemesis; one's worst enemy (figurative)
A person or thing that one finds impossible to deal with or defeat. Used casually to describe someone or something that is one's biggest weakness.
あの選手は彼にとって天敵だ。
That player is his nemesis.
数学は私の天敵だ。
Math is my worst enemy.
梅雨は洗濯物の天敵で、なかなか乾かない。
The rainy season is the nemesis of laundry — it just won't dry.
天敵 literally means "enemy given by nature" and is used both in biology and in everyday figurative speech.
COMPOSITION:
天 (heaven, natural) + 敵 (enemy).
COMMON PATTERNS:
- 〜の天敵: the natural enemy of ~
- 天敵がいない: to have no natural enemies
- 天敵を利用する: to use natural enemies (biological pest control)
USAGE:
The figurative sense is very common in casual speech. People use it to describe anything they find difficult to deal with:
- A rival: あの選手は彼の天敵だ
- A subject: 数学は天敵だ
- Weather: 梅雨は洗濯物の天敵だ
RELATED WORDS:
- 外敵: external enemy
- 捕食者: predator (scientific term)